TY - GEN A1 - Fischer, Annette A1 - Meissner, Andreas A1 - Weiß, Sabine ED - Yuan, Huang ED - Wittmann, Folker H. T1 - Microstructural peculiarities and mechanical properties of coronary stents T2 - Nonlocal Modelling of Failure of Materials, proceedings of an international workshop, University of Wuppertal, June 2007 Y1 - 2007 SN - 978-3-931681-87-6 SP - 91 EP - 104 PB - Aedificatio Publ. CY - Freiburg ER - TY - THES A1 - Weiß, Sabine T1 - Mikrostruktur- und Mikrotexturentwicklung bei der zyklischen Hochtemperaturverformung reiner kubisch-flächenzentrierter Metalle Y1 - 1998 SN - 3-8265-3372-0 PB - Shaker CY - Aachen ER - TY - GEN A1 - Hering, Daniel A1 - Kail, Jochem A1 - Eckert, Sabine A1 - Gerhard, Marc A1 - Meyer, Elisabeth I. A1 - Mutz, Michael A1 - Reich, Michael A1 - Weiss, Ilga T1 - Coarse Woody Debris Quantity and Distribution in Central European Streams T2 - International Review of Hydrobiology KW - coarse woody debris Y1 - 2000 U6 - https://doi.org/10.1002/(SICI)1522-2632(200003)85:1<5::AID-IROH5>3.0.CO;2-X SN - 1522-2632 VL - 85 IS - 1 SP - 5 EP - 23 ER - TY - GEN A1 - Bolz, Sebastian A1 - Oehring, Michael A1 - Lindemann, Janny A1 - Pyczak, Florian A1 - Paul, Jonathan A1 - Stark, Andreas A1 - Lippmann, Thomas A1 - Roth-Fagaraseanu, Dan A1 - Schreyer, Andreas A1 - Weiß, Sabine A1 - Schrüfer, Susanne T1 - Microstructure and mechanical properties of a forged beta-solidifying gamma TiAl alloy in different heat treatment conditions T2 - Intermetallics Y1 - 2015 VL - 2015 IS - 58 SP - 71 EP - 83 ER - TY - GEN A1 - Schulze, Marcus A1 - Seidlitz, Holger A1 - König, Franziska A1 - Weiß, Sabine T1 - Tribological Investigations of PVD Coated Multi-Layer Constructions T2 - Journal of Materials Science Research N2 - Multi-layer constructions become more and more relevant in lightweight applications due to their high strength to weight ratio. They offer excellent crash, damping and recycling properties. Also, the morphology of thermoplastic carbon fibre reinforced plastics (CFRP) render them interesting for large scale manufacturing processes. Nevertheless, a major disadvantage results in a poor resistance against wear and tear, e.g. erosion, which is attributed to weak hardness properties. Hence, this work deals with tribological investigations on orthotropic carbon fibre reinforced polymers (PA 6) either with protective ceramic coating or without. The chosen coating system is a well-known protective covering of metal components, e.g. metal cutting tools, produced by physical vapor deposition (PVD). To characterize the coating system on thermoplastic CFRP, standard analyzing methods are utilized, like optical and scanning electron microscopy (SEM). The tribological investigations are conducted by the tribological ball on disk method to generate wear tracks on the sample surfaces and hence to calculate the wear rates. These results are compared to literature findings with respect to a certain protective coating system (TiN) and a second nano-structured gel coating system, where both systems are deposited on a thermosetting material, i.e. carbon fibre reinforced epoxy resin, respectively. For this purpose the feasibility of depositing a protective ceramic layer on thermoplastic CFRP is demonstrated. First results on suitable surface pre-treatments have shown a significant influence on the coating quality. The improved performance regarding the wear behavior with respect to tribology compared to the poor substrate and existing technologies is shown additionally. KW - thermoplastic composites KW - protective coating systems KW - tribology KW - wear KW - physical vapour deposition Y1 - 2016 U6 - https://doi.org/10.5539/jmsr.v5n1p97 SN - 1927-0585 VL - 5 IS - 1 SP - 97 EP - 106 ER - TY - GEN A1 - Oehring, Michael A1 - Lindemann, Janny A1 - Pyczak, Florian A1 - Paul, Jonathan A1 - Stark, Andreas A1 - Lippmann, Thomas A1 - Schrüfer, Susanne A1 - Roth-Fagaraseanu, Dan A1 - Schreyer, Andreas A1 - Weiß, Sabine T1 - Microstructure and mechanical properties of a forged β-solidifying γ TiAl alloy in different heat treatment conditions T2 - Intermetallics N2 - In the cast condition g titanium aluminide alloys that solidify completely through the b phase are characterized by fine and homogeneous microstructures, weak textures and low segregation. For these reasons such alloys have a relatively good workability and can be closed-die forged without preceding ingot breakdown even if the alloys contain no large fractions of the b phase at the working temperature. The present work was devoted to a combined study of the constitution and microstructural morphologies that develop in various two-step heat treatments of a single-step forged b solidifying alloy. The study included high-energy X-ray diffraction for in situ investigations of the constitution at the heat treatment temperature. It was observed that the phase ransformations are quite sluggish in the material which results in fine microstructures and some conditions that significantly deviate from thermodynamic equilibrium. Further, tensile and creep testing was carried out on the different material conditions in order to identify the range in which the properties can be varied. It is found that this easily forgeable material exhibits comparable strength, ductility and creep strength as more conventional peritectically solidifying alloys. KW - TiAl KW - Titanium Aluminides KW - hot die forging KW - TNB-V4 Y1 - 2015 UR - http://www.sciencedirect.com/science/article/pii/S096697951400301X U6 - https://doi.org/10.1016/j.intermet.2014.11.008 SN - 0966-9795 VL - 2015 IS - 58 SP - 71 EP - 83 ER - TY - GEN A1 - Kazak, Fedor A1 - Weiß, Sabine T1 - Test procedure for fatigue investigations regarding structured sheet metal joints T2 - Materials Testing N2 - The topic of fatigue strength of joints of flat and honeycomb-structured thin sheets has not yet been adequately studied. This concerns, for example,the development of an appropriate test method. In many cases, there is still a lack of information, how effective joints of flat and structured sheet metals are in omparison with reference joints of flat sheets. Combinations of resistance spot-welded specimens of flat and honeycomb-structured thin sheets of deep-drawing steel DC04 with a thickness of 0.5 mm were examined. Adopted clamping plates were applied for the testing. Joined smooth specimens were used as a reference material. The analysis of the frequency [1] was applied for comparison. The fatigue limit of a joint of a flat and a structured sheet metal is not significantly affected by spot welding. The fatigue limit of these spot-welded joints is comparable to that of an non joined honeycomb-structured sheet. By means of frequency or stiffness analysis, stability and damage mechanisms of differently shaped joints were explained. The joining of bridges of the structure shows a better stability than the combination of honeycombs. The stiffness analysis is a favored method for the clarification of the damage mechanisms in a spot-welded joint. The reasons for the low fatigue strength values of the joined flat-structured specimens compared to flat-flat joints are strong notch effects in the bridge area and momentum effects by the structure height of the studied honeycomb structure. The spot weld with a pronounced indentation also affected the fatigue strength of both flat and structured joined sheet metals. Y1 - 2016 SN - 0025-5300 SN - 2195-8572 VL - 58 IS - 2 SP - 109 EP - 116 ER - TY - GEN A1 - Kazak, Fedor A1 - Weiß, Sabine T1 - Comparability of structured and flat reference specimens made of thin sheet metal T2 - Materials Testing N2 - The literature review reveals that the honeycomb-structured thin sheet metals are not adequately investigated with regard to their fatigue strength. A question that remains almost completely ignored in the process is the direct comparability of structured thin sheet metals with flat reference specimens. A thin sheet is not a classic specimen to determine the fatigue strength because of the known problem of the fracture mechanics. Structured thin sheet metals of deep-drawing steel DC04 with a thickness of 0.5 mm were examined. Flat specimens were used as reference material. The frequency analysis was used for comparison. Fundamental differences in the mechanical behavior between flat and structured sheets under cyclic load were observed. Whereas an extremely flat S-N curve in the low-cycle region with a high slope coefficient was observed for the smooth thin sheets, the structured specimens show a curve typical for notched specimens. Moreover, the smooth sheets have a specific cyclic hardening and/or softening behavior. The state of plane stress of a fine sheet in contrast to a multi-axial one for the structured sheet complicates the direct comparison. For this reason, such a comparison with respect to their fatigue strength in the Wohler diagram should only be considered with caution. Y1 - 2015 U6 - https://doi.org/10.3139/120.110748 SN - 0025-5300 SN - 2195-8572 VL - 57 IS - 6 SP - 567 EP - 573 ER - TY - GEN A1 - Weiß, Sabine A1 - Mitevski, Bojan T1 - Microstructure and Deformation of Coronary Stents from CoCr-Alloys with Different Designs T2 - Materials N2 - Coronary heart disease is still one of the most common sources for death in western industrial countries. Since 1986, a metal vessel scaffold (stent) has been inserted to prevent the vessel wall from collapsing. Most of these coronary stents are made from CrNiMo­steel (316L). Due to its austenitic structure, the material shows a good combination of strength, ductility, corrosion resistance, and biocompatibility. However, this material has some disadvantages like its non-MRI compatibility and its poor fluoroscopic visibility. Other typically used materials are the Co­Base alloys L-605 and F-562 which are MRI compatible as well as radiopaque. Another interesting fact is their excellent radial strength and therefore the ability to produce extra thin struts with increased strength. However, because of a strut diameter much less than 100 μm, the cross section consists of about 5 to 10 crystal grains (oligo­crystalline). Thus, very few or even just one grain can be responsible for the success or failure of the whole stent. To investigate the relation between microstructure, mechanical factors and stent design, commercially available Cobalt-Chromium stents were investigated with focus on distinct inhomogeneous plastic deformation due to crimping and dilation. A characteristic, material related deformation behavior with predominantly primary slip was identified to be responsible for the special properties of CoCr stents. Y1 - 2015 U6 - https://doi.org/10.3390/ma8052467 SN - 1996-1944 VL - 8 IS - 5 SP - 2467 EP - 2479 ER - TY - GEN A1 - Naveed, Muhammad A1 - Flores Renteria, Arturo A1 - Nebel, Daniel A1 - Weiß, Sabine T1 - Study of high velocity solid particle erosion behaviour of Ti2AlC MAX phase coatings T2 - Wear N2 - This research work provides information about the influence of Ti2AlC MAX phase coatings on the erosion resistance of Ti624 2alloy.Flat specimens were coated witha20 µm Ti2AlC film using an industrial siz emagnetron sputtering coater and annealed at 800 °C for 1h in vacuum for the formation of the MAX phase.The erosion resistance of the specimens was tested using high velocity particles at room temperature.The results indicate that the erosion resistance of Ti6242 has been significantly enhanced by the employment of MAX-phase coatings. This demonstrates the capability of using MAX phase coatings as erosion protective medium for engine components exposed to similar damage conditions. Additionally,the results show that uncoated Ti6242 samples with duplex microstructure have a better durability against erosion attack compared to uncoated samples with globular microstructure. KW - Erosion, MAX Phase Y1 - 2015 U6 - https://doi.org/10.1016/j.wear.2015.09.014 SN - 0043-1648 VL - 2015 IS - 342-343 SP - 391 EP - 397 ER - TY - GEN A1 - Naveed, Muhammad A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Investigation of the wear resistance properties of Cr/CrN multilayer coatings against sand erosion T2 - Conference Papers in Science N2 - The wear of metallic components used in gas and steam turbines due to erosive sand particles lead to a tremendous decrease in their lifetime. This wear can be reduced by the use of suitable erosion resistant coatings resulting in lower maintenance costs. In this context, multilayer Cr/CrN PVD coatings using an industrial coater was designed and applied on Inconel 718, a material which finds its application in gas turbines. A variation in the bimodal period has been induced in order to achieve an optimal coating architecture providing optimum properties needed for the erosion resistant coatings. The coating was deposited using a single Cr- target with an induction of N2 during the nitriding phase at a temperature of 480-500 °C and the coating thickness of 24-26 µm was kept constant throughout. The erosion tests were conducted at angles of 30°, 60° and 90°. The sand used for the test is an irregular shaped SiO2. The erosion tests were followed by a detailed microscopic examination of the eroded coating structure in combination with nanoindentation and scratch tests. KW - Cr/CrN multilayer, Erosion, PVD, Coatings Y1 - 2015 U6 - https://doi.org/10.1155/2015/873543 N1 - Article ID 873543 VL - 2015 SP - 1 EP - 10 ER - TY - CHAP A1 - Mlikota, Marjo A1 - Schmauder, Siegfried A1 - Mitevski, Bojan A1 - Weiß, Sabine ED - Deng, Jiamei ED - Liu, Quingjun T1 - Scientific Multiscale and Multidisciplinary Analysis of Deformation and Damage in the Case of Oligocrystalline Structures T2 - Computer Science and Engineering Technology N2 - This paper serves as an overview of the ongoing research in the field of multiscale and multidisciplinary analysis of deformation and damage in the case of oligocrystalline structures. The research focuses on experimental measurement and numerical calculation of ductile failure in the X2CrNiMo18-15-3 (AISI 316L) stainless steel. An embedding numerical technique is employed where crystal plasticity theory is used to represent plastic deformation in the material and element removal technique based on Rice&Tracey damage model for ductile void growth to simulate damage initiation inside the material, which is observed in the experiments. Additionally, the crystal plasticity model is supported by a hierarchical multiscale approach connecting nano-, micro- and meso-scales. Y1 - 2016 SN - 978-981-4651-00-4 SP - 113 EP - 118 PB - World Scientific Publishing CY - Singapore ER - TY - GEN A1 - Schulze, Marcus A1 - Seidlitz, Holger A1 - König, Franziska A1 - Weiß, Sabine T1 - Nanoindentation measurements of PVD coated multilayer constructions T2 - Journal of Achievements in Materials and Manufacturing Engineering N2 - Carbon fibre reinforced thermoplastics (CFRP) are intensively used in lightweight applications due to their high strength to weight ratio. In addition they offer good crash, damping and recycling properties. On the basis of their morphology they are suitable for large scale manufacturing processes. A major disadvantage consists of its poor hardness properties, which is again an important requirement to realize a good erosion and wear behaviour. Design/methodology/approach: In this work the application of orthotropic carbon fibre reinforced polymers (PA6), with protective TiAlN coatings, produced by physical vapor deposition (PVD), is investigated. The characterization of the coating is performed by nanoindentation tests, roughness measurements and scanning electron microscopy. Furthermore micro hardness tests on selected well prepared cross sections are conducted, to compare the coating quality with established coating systems. Findings: By applying TiAlN coating, the hardness of the CFRP samples can be increased substantially up to 15 GPa, in comparison to the basic substrate. In addition the quality of the coating surface can be improved significantly by plasma etching pre-treatment. Research limitations/implications: The presented findings are preliminary results to prove the application of a standard processed ceramic coating on new composite types for mass production. The PVD coating process as well as the utilized testing methods are suitable to realize hard coatings on thermoplastic CFRP. This effect can be exploited for several lightweight applications to increase the erosion and wear resistance of composite materials. Originality/value: The presented results show, that ceramic coatings can be deposited on standard thermoplastic CFRP with polyamide 6 matrix. Therewith it can be expected, that the PVD coating process can make a essential contribution to increase the range of applications. KW - Nanoindentation KW - Thermoplastic composites KW - TiAlN-coating Y1 - 2015 UR - http://www.journalamme.org/vol72_2/7221.pdf SN - 1734-8412 VL - 72 IS - 2 SP - 53 EP - 60 ER - TY - GEN A1 - Schulze, Marcus A1 - Seidlitz, Holger A1 - König, Franziska A1 - Weiß, Sabine T1 - Highly wear resistant PVD coatings for CFRP based multi-layer construction T2 - 11th International Scientific-Technical Conference on Advances in Plastics Technology (APT'15) Y1 - 2015 SN - 978-83-63555-47-4 CY - Gliwice ER - TY - GEN A1 - Stechow, Richard A1 - Ivanova, Irina A1 - Naveed, Muhammad A1 - Weiß, Sabine T1 - Sample Preparation of Worn Surfaces for EBSD Analysis T1 - Probenpräparation verschlissener Oberflächen für die EBSD Analyse T2 - Praktische Metallographie Y1 - 2016 U6 - https://doi.org/10.3139/147.110401 SN - 0032-678x SN - 2195-8599 VL - 53 IS - 6 SP - 352 EP - 359 ER - TY - GEN A1 - Naveed, Muhammad A1 - Stechow, Richard A1 - Bolz, Sebastian A1 - Hobusch, Katharina A1 - Weiß, Sabine T1 - Solid Particle Erosion of Heat Treated TNB-V4 at Ambient and Elevated Temperatures T2 - International Journal of Chemical, Molecular, Nuclear, Materials and Metallurgical Engineering Y1 - 2016 VL - 10 IS - 5 SP - 571 EP - 576 ER - TY - GEN A1 - Kazak, Fedor A1 - Schleuß, Leander A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin A1 - Weiß, Sabine T1 - Particularities of testing structured sheet metals in 3-point bending tests T2 - Materials Testing N2 - Thin sheet metals from deep drawing steel DC04 are very often used in the production of car body and case parts. Quality improvement of sheet metal components by new constructive solutions (structuring) as well as adapted joining technology is going on. Structured sheet metals differ from each other by their high bending stiffness. At the same time, they show certain anisotropy due to the structure. Therefore a typical testing method of structured semi-finished parts (single sheet metals, sandwiches)is the bending test. The literature review revealed that in many studies no special demands on tests of structured materials were made. This concerns particularly the structure arrangement, structure direction and structure location of the specimen relative to the mandrel position during bending tests, i. e., the direction of the fixed load relative to the structure. The aim of this study was to determine the influence of the test specification on flexural behavior. In the present paper, honeycomb-structured sheet metals were examined using 3-point bending tests. Bending stiffness and lightweight potential were calculated with respect to the location of load application and compared for different structure arrangements,directions and locations. The influence of the anisotropy on flexural behavior of the honeycomb-patterned sheet metals was moderate. Y1 - 2016 U6 - https://doi.org/10.3139/120.110883 SN - 0025-5300 SN - 2195-8572 VL - 58 IS - 6 SP - 495 EP - 500 ER - TY - GEN A1 - Naveed, Muhammad A1 - Flores Renteria, Arturo A1 - Weiß, Sabine T1 - Role of alloying elements during thermocyclic oxidation of β/γ-TiAl alloys at high temperatures T2 - Journal of Alloys and Compounds N2 - Gamma titanium aluminides are promising alloys known for their good mechanical properties and low densities, but their low oxidation resistance at high temperatures limits their application. This work discusses the thermocyclic oxidation behavior of newly developed β/γ-TiAl alloys at temperatures between 600 °C and 900 °C. An influence of β-stabilizing alloying elements like Nb and V on the oxidation of these alloys has been investigated here. The selected alloys are tested in an in-house developed thermocyclic furnace. The oxidation study is supported by gravimetric measurements along with Scanning Electron Microscopy (SEM) and Electron Diffraction Spectroscopy (EDS) mapping of the oxide layers. Additionally, phase formation after oxidation has been determined using X-Ray Diffraction (XRD). Results show that the Nb containing alloys are more oxidation resistant as compared to V containing alloys. The formation of a mixture of Al2O3 and TiO2 layers was found for all the alloys. The oxide kinetics controlled oxide growth and formation of various phases at different testing temperatures. KW - Aluminum oxide KW - γ-TiAl KW - thermocyclic oxidation KW - β-stabilizing elements Y1 - 2016 U6 - https://doi.org/10.1016/j.jallcom.2016.08.259 SN - 0925-8388 VL - 691 SP - 489 EP - 497 ER - TY - GEN A1 - Bambach, Markus A1 - Sizova, Irina A1 - Bolz, Sebastian A1 - Weiß, Sabine T1 - Devising Strain Hardening Models Using Kocks-Mecking Plots - A Comparison of Model Development for Titanium Aluminides and Case Hardening Steel T2 - Metals KW - titanium aluminides alloy KW - single phase steel KW - hot forming Y1 - 2016 U6 - https://doi.org/10.3390/met6090204 SN - 2075-4701 VL - 6 IS - 9 SP - 204 ER - TY - GEN A1 - Naveed, Muhammad A1 - Obrosov, Aleksei A1 - Zak, Andrzej A1 - Dudzinski, Wlodzimierz A1 - Volinsky, Alex A. A1 - Weiß, Sabine T1 - Sputtering Power Effects on Growth and Mechanical Properties of Cr2AlC MAX Phase Coatings T2 - Metals N2 - Coating growth and mechanical properties of nanolamellar Cr2AlC coatings at various sputtering power were investigated in the present study. Cr2AlC coating was deposited on the IN 718 superalloy and (100) Si wafers by DC magnetron sputtering at different sputtering powers. The structure and properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nanoindentation. It was found that coatings had columnar structure with nanocrystalline substructure. Deposition rate increased with the sputtering power. XRD results showed the presence of the Cr2AlC MAX phase, intermetallic AlCr2 and Cr7C3 carbide phases, along with the change in preferential coating growth orientation. TEM observations confirmed the occurrence of these phases, and the SAED patterns demonstrated significant texture of the coatings. Hardness values were measured in the range between 11–14 GPa, showing a slight increase with the sputtering power. KW - MAX Phase KW - Cr2AlC KW - TEM Y1 - 2016 U6 - https://doi.org/10.3390/met6110265 SN - 2075-4701 VL - 6 IS - 11 SP - 265 ER - TY - GEN A1 - Obrosov, Aleksei A1 - Naveed, Muhammad A1 - Volinsky, Alex A. A1 - Weiß, Sabine T1 - Substrate Frequency Effects on CrxN Coatings Deposited by DC Magnetron Sputtering T2 - Journal of Materials Engineering and Performance N2 - Controlled ion bombardment is a popular method to fabricate desirable coating structures and modify their properties. Substrate biasing at high frequencies is a possible technique, which allows higher ion density at the substrate compared with DC current bias. Moreover, high ion energy along with controlled adatom mobility would lead to improved coating growth. This paper focuses on a similar type of study, where effects of coating growth and properties of DC magnetron-sputtered chromium nitride (CrxN) coatings at various substrate bias frequencies are discussed. CrxN coatings were deposited by pulsed DC magnetron sputtering on Inconel 718 and (100) silicon substrates at 110, 160 and 280 kHz frequency at low duty cycle. Coating microstructure and morphology were studied by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), scratch adhesion testing and nanoindentation. Results indicate a transformation of columnar into glassy structure of CrxN coatings with the substrate bias frequency increase. This transformation is attributed to preferential formation of the Cr2N phase at high frequencies compared with CrN at low frequencies. Increase in frequency leads to an increase in deposition rate, which is believed to be due to increase in plasma ion density and energy of the incident adatoms. An increase in coating hardness along with decrease in elastic modulus was observed at high frequencies. Scratch tests show a slight increase in coating adhesion, whereas no clear increase in coating roughness can be found with the substrate bias frequency. KW - adhesion of coatings KW - CrN coatings KW - frequency KW - mechanical properties KW - microstructure KW - PVD KW - X-ray diffraction Y1 - 2016 UR - http://link.springer.com/article/10.1007/s11665-016-2426-4 U6 - https://doi.org/10.1007/s11665-016-2426-4 SN - 1544-1024 VL - 26 IS - 1 SP - 366 EP - 373 ER - TY - GEN A1 - Obrosov, Aleksei A1 - Gulyaev, Roman A1 - Zak, Andrzej A1 - Ratzke, Markus A1 - Naveed, Muhammad A1 - Dudzinski, Wlodzimierz A1 - Weiß, Sabine T1 - Chemical and Morphological Characterization of Magnetron Sputtered at Different Bias Voltages Cr-Al-C Coatings T2 - Materials N2 - MAX phases (M = transition metal, A = A-group element, and X = C/N) are of special interest because they possess a unique combination of the advantages of both metals and ceramics. Most attention is attracted to the ternary carbide Cr2AlC because of its excellent high-temperature oxidation, as well as hot corrosion resistance. Despite lots of publications, up to now the influence of bias voltage on the chemical bonding structure, surface morphology, and mechanical properties of the film is still not well understood. In the current study, Cr-Al-C films were deposited on silicon wafers (100) and Inconel 718 super alloy by dc magnetron sputtering with different substrate bias voltages and investigated using Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), and nanoindentation. Transmission Electron Microscopy (TEM) was used to analyze the correlation between the growth of the films and the coating microstructure. The XPS results confirm the presence of Cr2AlC MAX phase due to a negative shift of 0.6–0.9 eV of the Al2p to pure aluminum carbide peak. The XRD results reveal the presence of Cr2AlC MAX Phase and carbide phases, as well as intermetallic AlCr2. The film thickness decreases from 8.95 to 6.98 µm with increasing bias voltage. The coatings deposited at 90 V exhibit the lowest roughness (33 nm) and granular size (76 nm) combined with the highest hardness (15.9 GPa). The ratio of Al carbide to carbide-like carbon state changes from 0.12 to 0.22 and correlates with the mechanical properties of the coatings. TEM confirms the columnar structure, with a nanocrystalline substructure, of the films. KW - XPS KW - AFM KW - MAX phase KW - TEM KW - chemical bonding KW - surface morphology Y1 - 2017 UR - http://www.mdpi.com/1996-1944/10/2/156/htm U6 - https://doi.org/10.3390/ma10020156 SN - 1996-1944 VL - 10 IS - 2 SP - 156 ER - TY - GEN A1 - Obrosov, Aleksei A1 - Gulyaev, Roman A1 - Ratzke, Markus A1 - Volinsky, Alex A. A1 - Bolz, Sebastian A1 - Naveed, Muhammad A1 - Weiß, Sabine T1 - XPS and AFM Investigations of Ti-Al-N Coatings Fabricated Using DC Magnetron Sputtering at Various Nitrogen Flow Rates and Deposition Temperatures T2 - Metals N2 - Ti-Al-N coatings were deposited by direct current magnetron sputtering (DCMS) onto IN 718 at different nitrogen flow rates and deposition temperatures. The coatings’ properties were characterized using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) as well as nanoindentation. It was found that higher deposition temperature leads to higher surface roughness and nitrogen flux influences the shape of grains. According to XPS, the bonding structure of all coatings exhibited the (Ti,Al)N phase. Mechanical properties depend on the Al content within the films. The coating with the best mechanical properties (deposited at 500 °C and 20 standard cubic centimeters per minute (sccm)) was further deposited onto tungsten carbide (WC) cutting tools for cylindrical turning experiments. A quasi-constant flank wear was observed until a machining volume of 23,500 mm³. KW - Ti-Al-N coatings KW - DC magnetron sputtering KW - XPS KW - AFM KW - nitrogen flow rate KW - surface morphology Y1 - 2017 UR - http://www.mdpi.com/2075-4701/7/2/52/htm U6 - https://doi.org/10.3390/met7020052 SN - 2075-4701 VL - 7 IS - 2 SP - 52 ER - TY - CHAP A1 - Schulze, Marcus A1 - Seidlitz, Holger A1 - König, Franziska A1 - Weiß, Sabine ED - Dobrzański, Leszek A. T1 - Nanoindentation measurements of PVD coated multilayer constructions T2 - Programme and proceedings of the 22nd Winter International Scintific Conference on Achivements in Mechanical and Materials Engineering (AMME'15), Gliwice - Zakopane (Poland), 2015 Y1 - 2015 SN - 978-83-63553-39-5 PB - Gliwice CY - International OCSCO World Press ER - TY - GEN A1 - Obrosov, Aleksei A1 - Sutygina, Alina A1 - Volinsky, Alex A. A1 - Manakhov, Anton A1 - Weiß, Sabine A1 - Kashkarov, Egor B. T1 - Effect of Hydrogen Exposure on Mechanical and Tribological Behavior of CrₓN Coatings Deposited at Different Pressures on IN718 T2 - Materials N2 - In the current study, the properties of the CrₓN coatings deposited on the Inconel 718 superalloy using direct current reactive magnetron sputtering are investigated. The influence of working pressure on the microstructure, mechanical, and tribological properties of the CrₓN coatings before and after high-temperature hydrogen exposure is studied. The cross-sectional scanning electron micrographs indicate the columnar structure of the coatings, which changes from dense and compact columns to large columns with increasing working pressure. The Cr/N ratio increases from 1.4 to 1.9 with increasing working pressure from 300 to 900 mPa, respectively. X-ray diffraction analysis reveals a change from mixed hcp-Cr₂N and fcc-CrN structure to approximately stoichiometric Cr₂N phase. After gas-phase hydrogenation, the coating deposited at 300 mPa exhibits the lowest hydrogen absorption at 600 °C of all investigated coatings. The results indicate that the dense mixed cubic and hexagonal structure is preferential for hydrogen permeation resistance due to the presence of cubic phase with higher packing density in comparison to the hexagonal structure. After hydrogenation, no changes in phase composition were observed; however, a small amount of hydrogen is accumulated in the coatings. An increase of coating hardness and elastic modulus was observed after hydrogen exposure. Tribological tests reveal that hydrogenation leads to a decrease of the friction coefficient up to 20%–30%. The best value of 0.25 was reached for hydrogen exposed CrₓN coating deposited at 300 mPa. KW - CrₓN coatings KW - PVD KW - hydrogenation KW - tribology KW - mechanical properties KW - GDOES Y1 - 2017 UR - http://www.mdpi.com/1996-1944/10/5/563/htm U6 - https://doi.org/10.3390/ma10050563 SN - 1996-1944 VL - 10 IS - 5 SP - 563 ER - TY - CHAP A1 - Obrosov, Aleksei A1 - Kashkarov, Egor B. A1 - Weiß, Sabine A1 - Volinsky, Alex A. ED - Tiwari, Ashutosh T1 - Mechanical and tribological behaviour of hydrogenated CrxN coatings deposited at different pressure and voltages on IN718 T2 - American Advanced Materials Congress 2016 N2 - Hydrogen degradation is a serious problem in industrial applications like power plants (boilers, turbines), marine structures, car and aircraft components, as it leads to failures as well as to deterioration of properties. Inconel 718 is one of the most commonly used materials for these applications. Different metal nitrides like TiN coatings have been deposited in past to prevent hydrogen degradation, which are also known for their high hardness and good wear resistance [1, 2]. However, reports on hydrogen degradation of CrN coatings, which shows better oxidation and corrosion resistance, higher temperature stability and lower friction coefficient than TiN [3, 4] has not been reported till now. Despite a lot of publications about CrN films, up to now the effect of hydrogenation on mechanical and tribological properties of CrN coatings is still not completely understood. In the current work CrxN coatings were deposited by Direct Current Magnetron Sputtering (dcMS) on Inconel 718 substrate at different chamber pressures and substrate voltages. Substrate voltage is one of the most important process parameters which determines the structure of the coating and the adhesion between substrate and coating. Simultaneously a study of the chamber pressure is also needed to understand the deposited structure and growth rate because at higher pressures the high number of argon atoms reduce the number of ionized ions available for the deposition leading to low deposition rates [5]. Gas-phase hydrogenation of the samples was performed at a temperature of 600° C and hydrogen pressure of 2 atm. It was found that CrxN coatings are resistant against hydrogen exposure as compared to uncoated surfaces. The results of changes in the mechanical, tribological properties and phase composition of the coatings after hydrogenation are discussed. Coating microstructure was studied by scanning electron microscopy (SEM). The mechanical properties of the coatings were characterized by means of nanoindentation and scratch test. KW - CrxN coating KW - mechanical properties KW - microstructure KW - hydrogenation KW - XRD Y1 - 2016 SN - 978-91-88252-03-6 PB - VBRI Press CY - Linköping ER - TY - GEN A1 - Obrosov, Aleksei A1 - Naveed, Muhammad A1 - Krupp, Ulrich A1 - Solovev, Mikhail A1 - Weiß, Sabine T1 - Investigation of TiAlN HiPIMS coating deposited on the newly developed Ni-based superalloy AD730 N2 - The development of new alloys for gas turbine engines has been focused on withstanding against increasing service temperatures. AD730™ is a recently developed nickel-based superalloy for turbine disk applications with superior properties at 700°C, which is higher than the common service temperature for IN718. Use of coatings to enhance the properties of materials, such as wear resistance is widely known in various applications. This research presents an experimental study of TiAlN coatings, deposited onto AD730 superalloy using High Power Impulse Magnetron Sputtering (HiPIMS). Phase structure and chemical composition of the TiAlN films were characterized by X-ray diffractometry. Transmission electron microscopy as well as scanning electron microscopy were used to analyze the microstructure of the coating. Mechanical properties, including hardness, Young's modulus, and adhesion strength were measured using nanoindentation und scratch test. KW - TiAlN coating KW - HiPIMS KW - Ni-based superalloy KW - AD730 TEM XRD Y1 - 2016 UR - http://www.pse-conferences.net/poster-wednesday.html UR - http://www.pse-conferences.net/tl_files/abstract-print/PSE2016-PO3023.pdf N1 - 16th International Conference on Plasma Surface Engineering ER - TY - GEN A1 - Obrosov, Aleksei A1 - Naveed, Muhammad A1 - Weiß, Sabine T1 - Effect of pulse time on structure and mechanical properties of HPPMS deposited AlTiN coatings N2 - The use of PVD AlTiN as a protective coating on cutting tools is well known. With the introduction of pulsed deposition techniques like High Power Pulsed Sputtering (HPPMS), a possibility is provided to the coating developers to design their coatings by the variation in pulse parameters. To analyze the effect of pulse time HPPMS AlTiN coatings were deposited on Si (100) as well as 100Cr6 steel plates at a temperature of 500°C in a reactive gas environment. Oscilloscope measurements depicted a change in current-voltage characteristics with variation in pulse time. This influence the coating structure, deposition rates and phase formations as well. Nanoindentation results show a variation in the mechanical properties of the coatings with the change in pulse time. This study focuses on the potential of HPPMS technology for enhancement of mechanical and structural properties of AlTiN coating. KW - HPPMS KW - AlTiN KW - wear KW - cutting tools KW - pulse time Y1 - 2016 UR - http://www.pse-conferences.net/poster-wednesday.html UR - http://www.pse-conferences.net/tl_files/abstract-print/PSE2016-PO3055.pdf N1 - 16th International Conference on Plasma Surface Engineering ER - TY - CHAP A1 - Bambach, Markus A1 - Sizova, Irina A1 - Bolz, Sebastian A1 - Weiß, Sabine T1 - Development of a dynamic recrystallization model for a β-solidifying titanium aluminide alloy using Kocks-Mecking plots T2 - ESAFORM 2016, proceedings of the 19th International ESAFORM Conference on Material Forming, Nantes, France, 27-29 April 2016 Y1 - 2016 SN - 978-0-7354-1427-3 U6 - https://doi.org/10.1063/1.4963545 SP - 160002-1 EP - 160002-7 PB - AIP Publishing CY - Melville, New York ER - TY - GEN A1 - Kashkarov, Egor B. A1 - Nikitenkov, Nikolay A1 - Sutygina, Alina A1 - Laptev, Roman A1 - Bordulev, Yuriy A1 - Obrosov, Aleksei A1 - Liedke, Maciej O. A1 - Zak, Andrzej A1 - Weiß, Sabine T1 - Microstructure, defect structure and hydrogen trapping in zirconium alloy Zr-1Nb treated by plasma immersion Ti ion implantation and deposition T2 - Journal of Alloys and Compounds N2 - The effect of low energy plasma immersion ion implantation and deposition of titanium on microstructure, defect structure and hydrogen trapping in zirconium alloy Zr-1Nb was studied. Defect structure and distribution were analyzed by Doppler broadening using slow positron beam. The surface microstructure after modification is represented by nanostructured Ti grains with random orientation. The gradient distribution of titanium as well as vacancy type defects were analyzed. The concentration of vacancy type defects is rising with increasing bias voltage. Gas-phase hydrogenation of the Ti-modified Zr-1Nb alloy was performed at 400 °C for 60 min. The strong interaction of hydrogen with vacancy type defects was demonstrated. Two different changes in the defect structure after hydrogenation were observed: when a titanium film is formed on the surface (after deposition at 500 V) hydrogen trapping occurs with the formation of titanium hydride phases, while in the implanted layer (deposition at 1000 and 1500 V) hydrogen is trapped due to interaction with vacancy type defects. The physical basis of Ti diffusion and its influence on the evolution of defect structure after surface modification and hydrogenation were discussed. KW - Zirconium KW - Ion implantation KW - Titanium KW - Diffusion KW - Surface modification KW - Hydrogen trapping KW - Microstructure KW - Slow positrons KW - Doppler broadening KW - Defects Y1 - 2018 UR - http://www.sciencedirect.com/science/article/pii/S0925838817335879 U6 - https://doi.org/10.1016/j.jallcom.2017.10.151 SN - 0925-8388 VL - 732 SP - 80 EP - 87 ER - TY - GEN A1 - Shulepov, Ivan A. A1 - Kashkarov, Egor B. A1 - Stepanov, Igor B. A1 - Syrtanov, Maxim S. A1 - Sutygina, Alina A1 - Shanenkov, Ivan A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - The Formation of Composite Ti-Al-N Coatings Using Filtered Vacuum Arc Deposition with Separate Cathodes T2 - Metals N2 - Ti-Al-N coatings were deposited on high-speed steel substrates by filtered vacuum arc deposition (FVAD) during evaporation of aluminum and titanium cathodes. Distribution of elements, phase composition, and mechanical properties of Ti-Al-N coatings were investigated using Auger electron spectroscopy (AES), X-ray diffraction (XRD), transmission electron microscopy (TEM) and nanoindentation, respectively. Additionally, tribological tests and scratch tests of the coatings were performed. The stoichiometry of the coating changes from Ti0.6Al0.4N to Ti0.48Al0.52N with increasing aluminum arc current from 70 A to 90 A, respectively. XRD and TEM showed only face-centered cubic Ti-Al-N phase with preferred orientation of the crystallites in (220) direction with respect to the sample normal and without precipitates of AlN or intermetallics inside the coatings. Incorporation of Al into the TiN lattice caused shifting of the (220) reflex to a higher 2θ angle with increasing Al content. Low content and size of microdroplets were obtained using coaxial plasma filters, which provides good mechanical and tribological properties of the coatings. The highest value of microhardness (36 GPa) and the best wear-resistance were achieved for the coating with higher Al content, thus for Ti0.48Al0.52N. These coatings exhibit good adhesive properties up to 30 N load in the scratch tests. KW - filtered vacuum arc KW - deposition KW - TiAlN KW - separate cathodes KW - phase composition KW - hardness KW - wear-resistance Y1 - 2017 UR - http://www.mdpi.com/2075-4701/7/11/497/htm U6 - https://doi.org/10.3390/met7110497 SN - 2075-4701 VL - 7 IS - 11 ER - TY - GEN A1 - Severin, Stefanie A1 - Naveed, Muhammad A1 - Weiß, Sabine T1 - Effect of HPPMS pulse-frequency on plasma discharge and deposited AlTiN coating properties T2 - Advances in Materials Science and Engineering N2 - Coatings like TiAlN (titanium content more than 50 %) or AlTiN (aluminium content more than 50 %) are well established as hard and wear resistant tool coatings, often prepared by physical vapour deposition (PVD) like arc evaporation or direct current magnetron sputtering (dcMS). With increasing challenges of operating conditions, a constant need in improvement of mechanical properties is required to withstand extreme loading conditions. This can be obtained by a higher amount of ionized sputtered metal atoms during the deposition process. To increase the metal-ion flux a high-power pulse magnetron sputtering (HPPMS) was developed. In order to understand the relation between HPPMS process parameters and mechanical properties of the AlTiN coatings, the present study discusses how different pulse frequencies (for a constant pulse length) influence AlTiN coating structure growth and their mechanical properties. In addition, film deposition rate and phase formation are influenced by altering process parameters like pulse length and frequency. Hence, different pulse-frequencies produce specific coatings with corresponding properties for functional requirements. Based on the established findings, answers to new scientific queries along with the demand to further optimize these coatings for tool applications are required. KW - High power pulsed magnetron sputtering KW - Pulse frequency KW - Nanostructured AlTiN coatings KW - Mechanical properties Y1 - 2017 SN - 1687-8442 VL - 2017 ER - TY - GEN A1 - Doncheva Bambach, Margarita A1 - Bambach, Markus A1 - Sviridov, Alexander A1 - Weiß, Sabine T1 - New process chains involving additive manufacturing and metal forming - a chance for saving energy? T2 - Procedia Engineering KW - additive manufacturing KW - laser deposition welding KW - aluminium KW - energy consumption Y1 - 2017 U6 - https://doi.org/10.1016/j.proeng.2017.10.1049 SN - 1877-7058 N1 - International Conference on the Technology of Plasticity, ICTP 2017, 17-22 September 2017, Cambridge, United Kingdom VL - 207 SP - 1176 EP - 1181 ER - TY - GEN A1 - Obrosov, Aleksei A1 - Sutygina, Alina A1 - Manakhov, Anton A1 - Bolz, Sebastian A1 - Weiß, Sabine A1 - Kashkarov, Egor B. T1 - Oxidation Behavior of Zr–1Nb Corroded in Air at 400 °C after Plasma Immersion Titanium Implantation T2 - Metals N2 - In this paper, the influence of plasma immersion titanium implantation into the zirconium alloy Zr-1Nb on the oxidation behavior at 400 °C for 5, 24, 72, and 240 h in air under normal atmospheric pressure (101.3 kPa) was shown. The influence of implantation on the protective properties of the modified layer was shown. The valence of the oxides before and after implantation was analyzed by means of X-ray photoelectron spectroscopy (XPS). Grazing incidence X-ray diffraction (GIXRD) was carried out to examine the phase composition after titanium ion implantation and oxidation. Differential scanning calorimetry (DSC) revealed that titanium implantation exhibited effects of stabilizing the β phase. The formation of the t-ZrO2 and m-ZrO2 was observed during the oxidation of the as-received and modified Zr-1Nb. The measurement of weight gain showed an improvement in oxidation resistance of Ti implanted Zr-1Nb at the oxidation up to 24 h when compared with that of the as-received Zr-1Nb. However, at longer oxidation cycle the oxidation rate of Ti-implanted zirconium alloy is the same with the as-received alloy, which attributed to the layer thickness. Nevertheless, the corrosion of the Ti-implanted alloy is more uniform, while a local corrosion and cracks was detected on the surface of the as-received alloy. KW - zirconium alloy KW - titanium KW - ion implantation KW - PIII KW - oxidation KW - DSC KW - XPS KW - surface morphology KW - X-ray diffraction Y1 - 2018 UR - http://www.mdpi.com/2075-4701/8/1/27/htm U6 - https://doi.org/10.3390/met8010027 SN - 2075-4701 VL - 8 IS - 1 ER - TY - GEN A1 - Kashkarov, Egor B. A1 - Nikitenkov, Nikolay A1 - Sutygina, Alina A1 - Obrosov, Aleksei A1 - Manakhov, Anton A1 - Polčak, Josef A1 - Weiß, Sabine T1 - Hydrogen absorption by Ti-implanted Zr-1Nb alloy T2 - International journal of hydrogen energy N2 - This paper describes the hydrogenation behavior of Zr-1Nb alloy Ti-implanted by plasma immersion ion implantation (PIII). Hydrogen sorption kinetics of the Ti-modified alloy was investigated under gas-phase hydrogenation at 400 °C for 1 h. The influence of implantation time on the protective properties of the modified layer was shown. The lowest hydrogen absorption as well as the highest hydrogen trapping efficiency was achieved after PIII for 30 min. The main contribution to the reduction of hydrogen permeation is the formation of an oxide layer consisting of mixed TiO2 and ZrO2 on the modified surface of the alloy. X-ray photoelectron spectroscopy (XPS) revealed that PIII titanium oxide exists on the surface in the form of TiO2, which transforms to mixed Ti2O3 and TiO2 after hydrogenation. The thickness of the modified layer increases with implantation time that improves the efficiency of hydrogen trapping. All the absorbed hydrogen is gradually distributed in the modified layer and no hydrides are formed after hydrogenation in Ti-modified Zr-1Nb for 15 and 30 min. KW - Zirconium KW - Titanium implantation KW - Hydrogenation KW - X-ray photoelectron spectroscopy KW - Glow discharge optical emission spectroscopy KW - X-ray diffraction Y1 - 2018 UR - https://www.sciencedirect.com/science/article/pii/S0360319917346359 U6 - https://doi.org/10.1016/j.ijhydene.2017.12.003 SN - 0360-3199 VL - 43 IS - 4 SP - 2484 EP - 2491 ER - TY - GEN A1 - Kashkarov, Egor B. A1 - Obrosov, Aleksei A1 - Sutygina, Alina A1 - Uludintceva, Elena A1 - Mitrofanov, Andrei A1 - Weiß, Sabine T1 - Hydrogen Permeation, and Mechanical and Tribological Behavior, of CrNx Coatings Deposited at Various Bias Voltages on IN718 by Direct Current Reactive Sputtering T2 - Coatings N2 - In the current work, the microstructure, hydrogen permeability, and properties of chromium nitride (CrNₓ) thin films deposited on the Inconel 718 superalloy using direct current reactive sputtering are investigated. The influence of the substrate bias voltage on the crystal structure, mechanical, and tribological properties before and after hydrogen exposure was studied. It was found that increasing the substrate bias voltage leads to densification of the coating. X-ray diffraction (XRD) results reveal a change from mixed fcc-CrN + hcp-Cr₂N to the approximately stoichiometric hcp-Cr₂N phase with increasing substrate bias confirmed by wavelength-dispersive X-ray spectroscopy (WDS). The texture coefficients of (113), (110), and (111) planes vary significantly with increasing substrate bias voltage. The hydrogen permeability was measured by gas-phase hydrogenation. The CrN coating deposited at 60 V with mixed c-CrN and (113) textured hcp-Cr₂N phases exhibits the lowest hydrogen absorption at 873 K. It is suggested that the crystal orientation is only one parameter influencing the permeation resistance of the CrNx coating together with the film structure, the presence of mixing phases, and the packing density of the structure. After hydrogenation, the hardness increased for all coatings, which could be related to the formation of a Cr₂O₃ oxide film on the surface, as well as the defect formation after hydrogen loading. Tribological tests reveal that hydrogenation leads to a decrease of the friction coefficient by up to 40%. The lowest value of 0.25 ± 0.02 was reached for the CrNₓ coating deposited at 60 V after hydrogenation. KW - CrNx coatings KW - Physical Vapour Deposition (PVD) KW - hydrogenation KW - tribology KW - mechanical properties KW - X-ray diffraction Y1 - 2018 UR - http://www.mdpi.com/2079-6412/8/2/66/htm U6 - https://doi.org/10.3390/coatings8020066 SN - 2079-6412 N1 - Special Issue "Surface Preparation and Treatments for Enhancing the Coating Performance" VL - 8 IS - 2 ER - TY - GEN A1 - Evdokimov, Anton A1 - Obrosov, Aleksei A1 - Ossenbrink, Ralf A1 - Weiß, Sabine A1 - Michailov, Vesselin T1 - Mechanical properties of dissimilar steel-aluminum weld T2 - Materials Science and Engineering: A N2 - Knowledge of the properties of dissimilar welds is of great significance for the development of multi-material lightweight structures. In this study, stainless steel (1.4301) and aluminum alloy (6082-T6) sheets were welded in overlap configuration in keyhole mode. The resulting weld metals were investigated with respect to their mechanical properties. Several samples were cut out of different locations along the welds and their cross-sections were subjected to indentation testing and energy dispersive X-ray (EDS) analysis. Young's modulus E, yield stress σy, and strain hardening exponent n, were determined by means of reverse analysis of the indentation load (P) – depth (h) curves, allowing construction of true stress – true strain relations. An essential increase in yield stress in comparison to the one of the base alloys was observed inside the weld metal. In contrary, Young's modulus and strain hardening exponent of the welds were almost identical to corresponding values of the base steel metal. Due to the sensitivity of yield stress to the aluminum content, slight variations of the welding parameters lead to significant changes in elastic-plastic behavior of the weld metal. KW - Mechanical properties KW - Indentation KW - Reverse analysis KW - EDS measurements KW - Dissimilar steel aluminum welding KW - FEM Y1 - 2018 UR - https://www.sciencedirect.com/science/article/pii/S0921509318303563 U6 - https://doi.org/https://doi.org/10.1016/j.msea.2018.03.019 SN - 0921-5093 VL - Volume 722 SP - 242 EP - 254 ER - TY - GEN A1 - Obrosov, Aleksei A1 - Sutygina, Alina A1 - Kashkarov, Egor B. A1 - Weiß, Sabine T1 - Oxidation behavior of Zr–1Nb in air at 400°C after Titanium Plasma Immersion Ion Implantation N2 - Zirconium alloys have been widely used in nuclear reactors due to low thermal neutron capture cross-section, excellent corrosion resistance and acceptable mechanical properties [1, 2]. Nowadays several methods apply for improving hydrogen and corrosion resistance such as addition of stabilizing additives (yttrium) [3, 4], deposition of thin solid films [5, 6], micro-arc oxidation [7] and modification of the surface by electron beam [8, 9]. Despite the multiplicity of the methods hydrogen embrittlement is still a pressing issue. Previous results [10, 11] have shown the positive influence of plasma immersion titanium implantation on the hydrogenation behavior of Zr–1Nb and Zr–2.5 Nb. After Ti implantation hydrogen preferably accumulates in the modified surface layer comprising the implanted Ti. Furthermore, the hydrogen concentration is considerably less inside the zirconium modified sample than in the as-received samples. The integration of elements into the zirconium lattice can influence the valence of the surface and change corrosion and oxidation rates of the alloys. So it is very important not to decrease the zirconium oxidation resistance due to Ti implantation. Therefore, the purpose of this research is to study of the influence of Ti implantation on surface morphology, oxidation rate and phase structure of the Zr–1Nb alloy after oxidation on air at 400 0C for 5, 24, 72 and 240 h. The surface structure of the samples and their elemental composition were investigated with the scanning electron microscope Mira II XMH (Tescan) with energy dispersive x-ray spectroscopy system (EDS). X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC) as well as X-ray diffraction (XRD) was used to characterise the influence of titanium implantation on the oxidation behaviour. The results show that the oxidation kinetics after Ti modification of the zirconium alloy changed. Although the weight gain of the implanted sample remains approximately the same, it can be considered that Ti implantation stabilizes the oxide layer and has beneficial influence on the oxidation protection of Zr-1Nb. KW - Zr–1Nb KW - titanium ion implantation KW - oxidation KW - DSC KW - plasma immersion ion implantation (PIII) Y1 - 2018 UR - https://www.pse-conferences.net/tl_files/abstract-print/PSE2018-PO4029.pdf ER - TY - GEN A1 - Abang, Roger Atini A1 - Weiß, Sabine A1 - Krautz, Hans Joachim T1 - Impact of increased power plant cycling on the oxidation and corrosion of coal-fired superheater materials T2 - Fuel N2 - As power generation from variable renewable energy sources such as wind and solar power continues to increase in the future, fewer baseload power plants will be needed. As a result, high operational flexibility is becoming a vital requirement for conventional power plants to allow for the smooth integration of the variable renewable energy sources (v-RES) into the grid. To understand the impact of high operational flexibility (increased cycling) for coal-fired power plant materials, five commercial coal boiler superheater and reheater materials were investigated under isothermal and cyclic conditions for 1000 h each. The candidate alloys investigated were: T91, VM12-SHC, TP347-HFG, DMV304 HCu and DMV310 N. The results (weight change kinetics and metallographic analysis) after exposure at a metal surface temperature of 650 °C clearly showed the impact of increased flexibility on the corrosion and oxidation of the materials. Oxide growth (weight gain), metal loss, oxide spallation, and grain boundary attack were found to be more severe under cyclic conditions than under isothermal conditions. KW - Power plant flexibility, Isothermal oxidation, Cyclic oxidation, High temperature corrosion, Superheaters Y1 - 2018 U6 - https://doi.org/10.1016/j.fuel.2018.02.047 SN - 0016-2361 VL - 2018 IS - 220 SP - 521 EP - 534 ER - TY - GEN A1 - Santhanakrishnan Balakrishnan, Venkateswaran A1 - Seidlitz, Holger A1 - Weiß, Sabine T1 - Layup Configuration Effect on Notch Residual Strength in Composite Laminates T2 - Materials N2 - The current trend shows an increasing demand for composites due to their high stiffness to weight ratio and the recent progress in manufacturing and cost reduction of composites. To combine high strength and stiffness in a cost-effective way, composites are often joined with steel or aluminum. However, joining of thermoset composite materials is challenging because circular holes are often used to join them with their metal counterparts. These design based circular holes induce high stress concentration around the hole. The purpose of this paper is to focus on layup configuration and its impact on notch stress distribution. To ensure high quality and uniformity, the holes were machined by a 5 kW continuous wave (cw) CO2 laser. The stress distribution was evaluated and compared by using finite element analysis and Lekhnitskii’s equations. For further understanding, the notch strength of the laminates was compared and strain distributions were analyzed using the digital image correlation technique. KW - composite KW - notch stress KW - digital image correlation KW - ekhnitskii’s equation Y1 - 2018 U6 - https://doi.org/10.3390/ma11020308 SN - 1996-1944 VL - 11 IS - 2 ER - TY - GEN A1 - Kashkarov, Egor B. A1 - Ryabchikov, Alexander I. A1 - Kurochkin, Alexander A1 - Syrtanov, Maxim S. A1 - Shevelev, Alexey A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Hydrogen Interaction with Deep Surface Modified Zr-1Nb Alloy by High Intensity Ti Ion Implantation T2 - Metals N2 - A deep surface modified TiZr layer was fabricated by high-intensity low-energy titanium ion implantation into zirconium alloy Zr-1Nb. Gas-phase hydrogenation was performed to evaluate protective properties of the modified layer against hydrogen permeation into Zr-1Nb alloy. The effects of ion implantation and hydrogen on microstructure, phase composition and elemental distribution of TiZr layer were analyzed by scanning electron microscopy, X-ray diffraction, and glow-discharge optical emission spectroscopy, respectively. It was revealed that TiZr layer (~10 μm thickness) is represented by α′ + α(TiZr) lamellar microstructure with gradient distribution of Ti through the layer depth. It was shown that the formation of TiZr layer provides significant reduction of hydrogen uptake by zirconium alloy at 400 and 500 °C. Hydrogenation of the modified layer leads to refinement of lamellar plates and formation of more homogenous microstructure. Hydrogen desorption from Ti-implanted Zr-1Nb alloy was analyzed by thermal desorption spectroscopy. Hydrogen interaction with the surface modified TiZr layer, as well as its resistance properties, are discussed. KW - zirconium alloy KW - titanium KW - low energy ion implantation KW - hydrogen KW - sorption KW - microstructure KW - morphology KW - martensitic phase Y1 - 2018 UR - https://www.mdpi.com/2075-4701/8/12/1081/htm U6 - https://doi.org/10.3390/met8121081 SN - 2075-4701 VL - 8 IS - 12 ER - TY - GEN A1 - Gunther, Victor A1 - Yasenchuk, Yuri A1 - Chekalkin, Timofey A1 - Marchenko, Ekaterina A1 - Gunther, Sergey A1 - Baigonakova, Gulsharat A1 - Hodorenko, Valentina A1 - Kang, Ji-hoon A1 - Weiß, Sabine A1 - Obrosov, Aleksei T1 - Formation of pores and amorphous-nanocrystalline phases in porous TiNi alloys made by self-propagating high-temperature synthesis (SHS) T2 - Advanced Powder Technology N2 - The objective of this study was to examine the mechanism how the surface of porous TiNi compounds produced by SHS method evolves. The prepared samples were investigated using light-microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive x-ray spectroscopy (EDS). The results indicated that the surface of all pores is represented by a granular stratum due to dendrite liquation by peritectic crystallization mechanism. The voids of 2–15 μm in size are formed owing to a capillary spreading of the liquid. Reaction gases with dissociated carbon, nitrogen, and oxygen are responsible for heat-and-mass transfer through the forming pores. High pressure-temperature effect of reaction gases on the melt causes the forming voids to coalesce, as well as transfers the peritectic liquid (PL) throughout the open pores catalyzing a distinctive spitted topography. It is through the chemisorption of gasiform nonmetallics by the pore surface melt, where these impurities are chemically bound, that it was formed a massive corrosion-resistant amorphous-nanocrystalline stratified shell deduced as an intermetallic oxycarbonitride layer. KW - Porous TiNi alloys KW - SHS KW - Pore formation KW - Surface structures KW - Heat-and-mass transfer Y1 - 2019 UR - https://www.sciencedirect.com/science/article/pii/S092188311830387X?via%3Dihub U6 - https://doi.org/10.1016/j.apt.2018.12.011 SN - 0921-8831 VL - 30 IS - 4 SP - 673 EP - 680 ER - TY - GEN A1 - Yasenchuk, Yuri A1 - Gunther, Victor A1 - Marchenko, Ekaterina A1 - Chekalkin, Timofey A1 - Baigonakova, Gulsharat A1 - Hodorenko, Valentina A1 - Gunther, Sergey A1 - Kang, Ji-hoon A1 - Weiß, Sabine A1 - Obrosov, Aleksei T1 - Formation of mineral phases in self-propagating high-temperature synthesis (SHS) of porous TiNi alloy T2 - Materials Research Express N2 - The complex structural-phase composition, morphology and elemental composition of surface and nonmetallics in porous TiNi compounds produced by self-propagating high-temperature synthesis (SHS) in a flow reactor in the layer-by-layer combustion mode were analyzed. The samples were investigated using light microscopy (LM), X-ray diffraction (XRD), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and energy dispersive X-ray spectroscopy (EDS). The findings indicate that in addition to the TiNi and Ti2Ni intermetallic constituents, the pore's surface contains numerous Ti4Ni2(O,N,C) nanocrystalline oxycarbonitrides, spinels, polysilicates, and residual amorphous phases. The elemental composition of the surface and crystalline inclusions is investigated by the EDS method. LM, SEM, TEM, and EDS instrumental examination revealed the entire surface comprising a continuous shell of intermetallic superficial bulb-shaped structures, as well as crystalline inclusions of polysilicates and spinels in the intergranular peritectic phase. Prominent morphology was confirmed to appear throughout the pore's surface owing to the interaction of the peritectic liquid (PL) with reaction gases. The epitaxial, nanocrystalline strata of intermetallic oxycarbonitrides were shown to have the intricate nature. Reaction gases chemisorbed by the PL are responsible for the continuous and dense substrate, which ultrafine structure modulates a high corrosion resistance. On the contrary, the sparse and foamy overlay resulted from a convective transfer of the PL by reaction gases facilitates in vivo bio-integration of the alloy. Overall, this sheds light on and may be more indicative of the complex role of superficial strata and nonmetallic crystals in enhanced biocompatibility of the unwrought porous TiNi alloy. KW - Porous TiNi alloys KW - SHS KW - Pore formation KW - Surface structures KW - Reaction gases KW - Amorphous layer Y1 - 2019 UR - https://iopscience.iop.org/article/10.1088/2053-1591/ab01a1 U6 - https://doi.org/10.1088/2053-1591/ab01a1 SN - 2053-1591 VL - 6 IS - 5 ER - TY - GEN A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Djellabi, Ridha A1 - Samad, Mohammed Abdul A1 - Touhami, Mohamed Zine A1 - Montagne, Alex A1 - Iost, Alain A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Rapid and enhanced recovery of poly-dispersed nonionic surfactant (TX-100) from organic mediums using dehydrated and rehydrated kaolin T2 - Applied Clay Science N2 - The recovery of surfactants from organic mediums is of great economic and environmental interests in the field of petrochemicals sector. The aim of this study was to recover poly-dispersed nonionic surfactant (TX-100) from organic medium by the use of dehydrated and rehydrated kaolin. It was found that the presence of water after kaolin rehydration decreases considerably the amount of TX-100 adsorption from 28.7 μmol.g−1 onto dehydrated kaolin to 23.4 μmol.g−1 onto rehydrated kaolin. The estimation of the number of statistical layers of water deposited on kaolin was observed to be about 7 to 9. The effect of type of solvents (heptane, cyclohexane and benzene) on the adsorption onto rehydrated kaolin revealed a reduction in the adsorbed quantity; the adsorbed amounts were found to be 28.7 μmol.g−1, 26.7 μmol.g−1 and 24.2 μmol.g−1 in heptane, cycloheptane and benzene phases, respectively. On the other hand, it was observed that a temperature increased from 20 °C to 35 °C and 45 °C negatively affects the adsorption of TX-100 onto dehydrated and/or hydrated kaolin in heptane medium. KW - Adsorption KW - Organic medium KW - Surfactant recovery KW - Dehydrated/rehydrated kaolin KW - Petrochemical pollution Y1 - 2019 U6 - https://doi.org/10.1016/j.clay.2019.05.004 SN - 0169-1317 VL - 177 SP - 43 EP - 50 ER - TY - GEN A1 - Santhanakrishnan Balakrishnan, Venkateswaran A1 - Obrosov, Aleksei A1 - Kuke, Felix A1 - Seidlitz, Holger A1 - Weiß, Sabine T1 - Influence of metal surface preparation on the flexural strength and impact damage behaviour of thermoplastic FRP reinforced metal laminate made by press forming T2 - Composites Part B: Engineering N2 - In this paper the relationship between surface energy and flexural strength of metal laminate made by reinforcing glass fibre reinforced polymer on steel surfaces was investigated. Sand blasting was performed on 22MnB5 steel surface. This steel was stacked together with layers of unidirectional glass/polyamide-6 prepreg, followed by pressing in a hot press. Influenced parameters are pressure, temperature and time. 3D profilometer analysis was used to investigate the roughness profile on the surface of the steel generated by the sand blasting. The surface energy of the steel surface was calculated from a set of contact angles measured by three different liquids. To identify the optimal surface treatment, the variation of surface energy, flexural strength and roughness of the steel surface was determined as function of the surface treatment. Surface roughness (Ra of 1.08 μm), results indicate that increasing surface roughness leads to improvement in flexural modulus. The increase further leads to decrease in flexural modulus. In addition, the influence of surface energy and flexural strength on the impact damage behaviour was investigated too. The results showed that the sample with highest flexural modulus had the lowest impact-induced damage area. KW - Fiber reinforced plastic (FRP) KW - FRP reinforced metal composite KW - Sand blasting surface treatment KW - Surface energy KW - Contact angle Y1 - 2019 UR - https://www.sciencedirect.com/science/article/pii/S135983681930318X U6 - https://doi.org/10.1016/j.compositesb.2019.05.094 SN - 1359-8368 VL - 173 ER - TY - GEN A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Samad, Mohammed Abdul A1 - Montagne, Alex A1 - Kosman, Stephania A1 - Megias, Alberto A1 - Iost, Alain A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Biotribocorrosion behaviour of newly developed nanostructured near β-types Titanium based Alloys for Biomedical Applications T2 - nanoMAT2019 – 2nd International Conference on Nanomaterials and Their Applications N2 - The biotribocorrosion behavior of newly developed nanocristalline near β-types Ti-15Nb and Ti-15Mo alloys surfaces, sintered by powder metallurgy and sequentially milled, has been investigated in SBF simulated body fluid (PBS solution) at OCP, an applied potential in the passive region and EIS. Reciprocating sliding tests using a ball-on-plate tribometer under differentes applied loads 3, 7 and 10 N load and anodic potentials were applied to evaluate the effect of applied lad and the effect of Nb and Mo elements on tribocorrosion behaviors of samples. Results showed that, Ti-Nb exhibited better anticorrosive properties than Ti-Mo. Under tribological action the nanostructured both of alloys showed similar friction coefficient, while Ti-Nb present lower tendency to corrosion compared to Ti-Mo. Furthermore, Nb diffusion increased the repassivation rate with respect to Ti-Mo surfaces due to its stable passive film. Due to the high chemical reaction rate in β-type Ti-15Mo alloy as compared to Ti-15Nb. The β- Ti-15Nb showed lower volume loss, lower friction coefficient values and exhibited better corrosion resistance during tribocorrosion tests than Ti-15Mo. Prevailing electrochemical conditions between -1 and 2 V influences the wear accelerated corrosion by increasing it with the applied potential and slightly increases the mechanical wear. Also, wear accelerated corrosion can be predicted by existing models as a function of electrochemical and mechanical parameters of the titanium alloys. However, considering biomedical applications, the β- Ti15 Mo and Ti15Nb alloys may be good candidates with low elastic modulus and without toxic alloying elements. KW - Biotribocorrosion KW - titanium based alloys KW - Biomedical Applications Y1 - 2019 UR - http://nanomat2019.org/wp-content/uploads/2019/04/Book-of-Abstracts-nanomath2019.pdf SP - 170 ER - TY - GEN A1 - Obrosov, Aleksei A1 - Yasenchuk, Yuri A1 - Marchenko, Ekaterina A1 - Gunther, Victor A1 - Radkevich, Andrey A1 - Kokorev, Oleg A1 - Gunther, Sergey A1 - Baigonakova, Gulsharat A1 - Hodorenko, Valentina A1 - Chekalkin, Timofey A1 - Kang, Ji-hoon A1 - Weiß, Sabine T1 - Biocompatibility and Clinical Application of Porous TiNi Alloys Made by Self-Propagating High-Temperature Synthesis (SHS) T2 - Materials N2 - Porous TiNi alloys fabricated by self-propagating high-temperature synthesis (SHS) are biomaterials designed for medical application in substituting tissue lesions and they were clinically deployed more than 30 years ago. The SHS process, as a very fast and economically justified route of powder metallurgy, has distinctive features which impart special attributes to the resultant implant, facilitating its integration in terms of bio-mechanical/chemical compatibility. On the phenomenological level, the fact of high biocompatibility of porous SHS TiNi (PTN) material in vivo has been recognized and is not in dispute presently, but the rationale is somewhat disputable. The features of the SHS TiNi process led to a multifarious intermetallic Ti4Ni2(O,N,C)-based constituents in the amorphous-nanocrystalline superficial layer which entirely conceals the matrix and enhances the corrosion resistance of the unwrought alloy. In the current article, we briefly explore issues of the high biocompatibility level on which additional studies could be carried out, as well as recent progress and key fields of clinical application, yet allowing innovative solutions. KW - porous SHS TiNi KW - biocompatibility KW - rheological similarity KW - corrosion resistance KW - bone substitution Y1 - 2019 UR - https://www.mdpi.com/1996-1944/12/15/2405/htm#B2-materials-12-02405 U6 - https://doi.org/10.3390/ma12152405 SN - 1996-1944 VL - 12 IS - 15 ER - TY - GEN A1 - Bouaksa, Fethia A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Djellabi, Ridha A1 - Touhami, Mohamed Zine A1 - Iost, Alain A1 - Montagne, Alex A1 - Kosman, Stephania A1 - Weiß, Sabine T1 - Effect of Thermocyclic Treatment with Different Cooling Rates on the Mechanical Characteristics of 42CD4 Low-Alloy Steel T2 - Defect and Diffusion Forum N2 - The aim of this study was to investigate the influence of thermo-cyclic treatments on the mechanical characteristics (Hardness and Resilience) of low-alloy 42CD4 steel. Thermocyclic treatment on 42CD4 steel was operated for four cycles at 850 °C for 30 min. After each cycle, the steel sample was cooled in different medium (open air and water) in order to check the effect of the cooling rate on the microstructure characteristics. It was found that the cooling rate can affect the mechanical characteristics of the steel. The hardness values of steel cooled in water were higher than those of steel cooled in air. Additionally, there was an increase in the resilience of steel sample with the increase of thermocyclic number. KW - Austenization KW - Grain Refinement KW - Grain Size KW - Hardness KW - Resilience KW - Thermocyclic Y1 - 2019 UR - https://www.scientific.net/DDF.397.169 U6 - https://doi.org/10.4028/www.scientific.net/DDF.397.169 SN - 1662-9507 VL - 397 SP - 169 EP - 178 ER - TY - GEN A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Samad, Mohammed Abdul A1 - Djellabi, Ridha A1 - Montagne, Alex A1 - Mejias, Alberto A1 - Kossman, Stephania A1 - Iost, Alain A1 - Purnama, Agung A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Effect of Molybdenum Content on Structural, Mechanical, and Tribological Properties of Hot Isostatically Pressed β-Type Titanium Alloys for Orthopedic Applications T2 - Journal of Materials Engineering and Performance N2 - Aiming to develop alloys with better properties for orthopedic applications, the focus of the present research was to evaluate the effect of Mo at.% content on structural, mechanical, and tribological properties of hot isostatically pressed Ti-xMo (x = 4, 8, 12, 15, and 20 at.%) alloys. The structural evolution, mechanical properties, and tribological behavior of the nanostructured Ti-xMo alloys were evaluated using x-ray diffraction, scanning electron microscope, and ball-on-disk tribometer. Wear tests were conducted under different applied loads of 2, 8, and 16 N. Experimental results indicated that the structural evolution and morphological changes of the milled alloys were sensitive to their molybdenum (Mo) content. The morphological characterization showed that the crystallite size and the particle size decreased with increasing Mo content (at.%) reaching the lowest values of 27 and 26 nm in the case of Ti-15Mo and Ti-20Mo, respectively. On the other hand, the coefficient of friction and wear rates were found to be decreasing with increasing Mo content. KW - friction behavior KW - hot isostatic pressing KW - milling KW - nanobiomaterials KW - Ti-Mo alloy KW - β-type titanium alloy KW - tribology KW - wear resistance Y1 - 2019 UR - https://link.springer.com/article/10.1007/s11665-019-04348-w U6 - https://doi.org/10.1007/s11665-019-04348-w SN - 1059-9495 VL - 28 IS - 10 SP - 5988 EP - 5999 ER - TY - GEN A1 - Obrosov, Aleksei A1 - Kashkarov, Egor B. A1 - Sharma, A. A1 - Weiß, Sabine T1 - Microstructure and defect structure of Zr-1Nb alloy deep surface modified by high Intensity Ti Ion implantation T2 - MC Microscopy Conference, 01-05 September 2019, Berlin, Abstracts N2 - A deep surface modified TiZr layer was fabricated by high-intensity low-energy titanium ion implantation into zirconium alloy Zr-1Nb alloy with the various dose in the range of (5.4–9.56) × 1020 ion/cm2. The gradient distribution of titanium as well as vacancy type defects were analysed. The effects of ion implantation on microstructure, phase composition and elemental distribution of TiZr layer were analysed by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and glow-discharge optical emission spectroscopy, respectively. The results show the appearance of Zr-Ti intermetallic phases of different stoichiometry after Ti implantation. The intermetallic phases are transformed from both Zr0.7Ti0.3 and Zr0.5Ti0.5 to single Zr0.6Ti0.4 phase with the increase in the implantation dose. The depth of Ti penetration into the bulk of Zr increases from 6 to 13 μm with the implantation dose. The higher current density (170 mA/cm2) leads to the increase in the grain size and surface roughness. It was revealed that TiZr layer (~10 μm thickness) is represented by α′ + α(TiZr) lamellar microstructure with gradient distribution of Ti through the layer depth. Transmission electron microscopy was used for investigation of the physical basis of Ti diffusion and its influence on the evolution of the defect structure after surface modification. Furthermore, it was found that on the surface between substrate and implanted layer was found an amorphous layer, which occur as a result of further stress accumulations from the higher implantation doses. Y1 - 2019 UR - https://epub.uni-regensburg.de/40685/1/MC%202019_Proceedings.pdf SP - 86 CY - Berlin ER - TY - GEN A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Dekhil, Leila A1 - Samad, Mohammed Abdul A1 - Djellabi, Ridha A1 - Kosman, Stephania A1 - Montagne, Alex A1 - Iost, Alain A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Effect of sintering temperature on structure and tribological properties of nanostructured Ti–15Mo alloy for biomedical applications T2 - Transactions of Nonferrous Metals Society of China N2 - The effect of sintering temperature (1073–1373 K) on the structural and tribological properties of nanostructured ball-milled β-type Ti–15Mo samples was investigated. The prepared samples were characterized using various apperatus such as X-ray diffractometer, scanning electron microscope (SEM) and ball-on-plate type oscillating tribometer. Wear tests were conducted under different applied loads (2, 8 and 16 N). Structural results showed that the mean pore and crystallite size continuously decreased with increasing sintering temperature to reach the lowest values of 4 nm and 29 nm at 1373 K, respectively. The relative density of the sintered sample at 1373 K was as high as 97.0%. Moreover, a higher sintering temperature resulted in higher relative density, greater hardness and elastic modulus of the sample. It was observed that both the friction coefficient and wear rate were lower in the sample sintered at 1373 K which was attributed to the closed porosity. KW - Ti–15Mo KW - wear KW - tribological behaviour KW - nanotribology KW - sintering KW - biomedical applications Y1 - 2019 UR - https://www.sciencedirect.com/science/article/pii/S100363261965137X#! U6 - https://doi.org/10.1016/S1003-6326(19)65137-X SN - 1003-6326 VL - 29 IS - 11 SP - 2310 EP - 2320 ER - TY - GEN A1 - Ermilova, Evgeniia A1 - Kazak, Fedor A1 - Weiß, Sabine T1 - Stability of structured sheet metals during buckling T2 - Materials Testing N2 - Structured materials can be a progressive alternative to commonly used flat sheets. There is an enormous range of possibilities for using structured sheet metals due to their better stability. However, the effective use of these materials as well as their implementation in production requires precise knowledge about specific properties of structured sheet metals. The aim of this work is to obtain new knowledge about stiffness and stability during the deformation of this material. The structured sheet metals were investigated by means of buckling tests. The steel type investigated is a commonly used deep-drawing steel DC04. Six types of structure arrangements were compared to non-structured (flat) specimens as a reference. The influence of the type of structure arrangement as well as the deformation speed on the mechanical properties was investigated. KW - Structured metals KW - flat sheet metals KW - buckling test KW - stiffness KW - stability Y1 - 2019 UR - https://www.hanser-elibrary.com/doi/10.3139/120.111403 U6 - https://doi.org/10.3139/120.111403 SN - 2195-8572 SN - 0025-5300 VL - 61 IS - 10 SP - 929 EP - 935 ER - TY - GEN A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Dekhil, Leila A1 - Samad, Mohammed Abdul A1 - Montagne, Alex A1 - Mejias, Alberto A1 - Iost, Alain A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Structural characterization of developed near β-Type Titanium Alloys (Ti-25NbxZr) for biomedical Applications T2 - 3rd International Conference on Mechanics and Materials : ICMM’2019 11-12 November 2019. Setif, Algeria, Abstracts book N2 - The osteoarthritis and degenerative diseases osteoporosis as well as trauma lead to the bone mechanical properties degradation due to absence of normal biological self healing processes or excessive loading [1–5]. These problems solution are artificial biomaterials, as surgical implantation of appropriate shapes helps restore function for the otherwise functionally compromised structures [1–5]. Biocompatibility is considered to be optimal once tissue neoformation and later function occurs around implantable devices [6]. The efficacy of biomaterials implants is determined mostly by their surface characteristics such as microstructure, surface morphology, composition and biological properties [2]. Aiming to develop alloys with better properties for orthopedic applications, the focus of the present research was to evaluate the effect of Zr at. % content on structural, mechanical and tribological properties of hot isostatically pressed Ti-25Nb-xZr (x = 5, 10, 15, 20 and 25 at. %) alloys. The structural evolution, and mechanical properties of the nanostructured Ti-Nb-xZr alloys were evaluated using X-Ray diffraction, scanning electron microscope. The mechanical properties were performed using Vickers hardness and berkovich nanoindentation. Experimental results indicated that the structural evolution and morphological changes of the milled alloys were sensitive to their Zirconium (at. %) content. The morphological characterization showed that the crystallite size and the particle size decreased with increasing Zr content (at. %). As well, as the Zr was added to the Ti-25NbXZr system, there was a clear decrease in the Vickers hardness and young’s modulus. On the other hand, the coefficient of friction and wear rates were found to be decreasing with increasing Zr content. KW - Ti-Nb-Zr alloys KW - Nanobiomaterials KW - tribological behaviour KW - Sintering KW - Biomedical applications Y1 - 2019 UR - https://drive.google.com/file/d/1XCFz_8p3aAacxwT1bWgK_rljAL5_oEXS/view SP - 224 EP - 225 CY - Setif, Algeria ER - TY - GEN A1 - Khalil, S. A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Smata, L. A1 - Montagne, Alex A1 - Mejias, Alberto A1 - Kossman, Stephania A1 - Iost, Alain A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Synthèse et caractérisation structurale d’un composé nanostructuré de Ti, Mo et Zr pour applications biomédicales T2 - 3rd International Conference on Mechanics and Materials : ICMM’2019 11-12 November 2019. Setif, Algeria, Abstracts book N2 - Le milieu médical est un perpétuel demandeur de biomatériaux compatibles surtout en orthopédie. Effectivement le nombre important d’arthroplasties effectuées chaque année ne cesse d’augmenter dans le monde, non seulement du fait vieillissement de la population (à partir de 65 ans), mais aussi de demandes de patients plus jeunes entre 45 ans et 55 ans. Actuellement, les composés à base de titane Ti sont largement utilisés comme des biomatériaux pour leur biocompatibilité, leur résistance à la corrosion et leur faible module d’élasticité. Le molybdène et le zirconium sont parmi les meilleurs éléments alliés parce qu’ils sont non toxiques et non allergiques et offrent d’excellentes propriétés. De plus,Le Zr peut augmenter la trempabilité et la résistance à la corrosion de l'alliage . Mo est un élément fort stabilisant pour la phase des alliages de titane et les alliages à base de Ti-Mo présentent des propriétés mécaniques adéquates compatibilité et bonne cyto-compatibilité . Par conséquent, le système Ti-Mo-Zr, qui a montré une bonnes performances et de magnifiques perspectives dans l’application de biomatériaux, a été intensivementétudié [1,2,3]. Cependant, les alliages de Ti largement utilisés, tels que les interstitiels extra-low (ELI) Ti-6Al-4V (wt.% en poids ), Ti- 5Al-2,5 Fe et Ti-6Al-7Nb, ont le risque de libérer de l'aluminium toxique (Al) et les Ions de vanadium (V) in vivo, ce qui peut causer des problèmes de santé, comme la maladie d’Alzheimer et la neuropathie[4].La métallurgie des poudres (MP), y compris la méthode de mixture des composants en poudre, qui consiste à fritter titane en poudre ou ses mélanges avec d’autres composants en poudre, est un procédé économique à moindre cout. La nanotechnologie est intervenue dans la structuration des biomatériaux à l’échelle nanométrique (entre1nmet 100 nm) par soucis d’amélioration des propriétés mécanique surtout le module de Young. KW - Biomatériaux, KW - Ti-Mo-Zr KW - nanomatériaux KW - caractérisation structurale KW - broyage mécanique Y1 - 2019 UR - https://drive.google.com/file/d/1XCFz_8p3aAacxwT1bWgK_rljAL5_oEXS/view SP - 243 EP - 244 CY - Setif, Algeria ER - TY - GEN A1 - Shapovalov, Oleg A1 - Gaal, Mate A1 - Hönig, Gerald A1 - Gradt, Thomas A1 - Weiß, Sabine ED - Ochmann, Martin ED - Vorländer, Michael ED - Fels, Janina T1 - Temperature dependence of the propagation speed of a longitudinal wave in different solids for use as a wedge material in an extreme-temperature-resistant ultrasonic transducer T2 - Proceedings of the 23rd International Congress on Acoustics : integrating 4th EAA Euroregio 2019 : 9-13 September 2019 in Aachen, Germany N2 - In special cases of angle beam ultrasonic measurement – e.g. defect detection in hot solids as well as flow measurement of liquid gases or energy storage mediums [1] – the applied transducer has to withstand extreme temperatures. Since the irradiation angle into the specific material is determined not only by wedge design, but also by the speed of sound in both the wedge material and the tested object, the developer must take into account the speed of the wave propagation in a wedge material over the whole temperature range of transducers application. In this study we investigate the temperature dependence of the speed of longitudinal wave propagation in 10 different materials in the range from -200 °C to 400 °C. The investigated materials belong to different material classes (ceramics, glass, as well as ferrous and non-ferrous metals) and are all temperature-resistant up to at least 600 °C, and therefore applicable as wedge materials in an ultrasonic transducer for use at extreme temperatures. KW - Ultrasonic Transducer KW - Speed of sound KW - Longitudinal Wave KW - Temperature Y1 - 2019 UR - http://publications.rwth-aachen.de/record/770364/files/770364.pdf SN - 978-3-939296-15-7 U6 - https://doi.org/10.18154/RWTH-CONV-239953 SN - 2226-7808 SN - 2415-1599 VL - 2019 SP - 4754 EP - 4760 CY - Aachen ER - TY - GEN A1 - Marchenko, Ekaterina A1 - Yasenchuk, Yuri A1 - Gunther, Sergey A1 - Baigonakova, Gulsharat A1 - Gunther, Victor A1 - Chekalkin, Timofey A1 - Weiß, Sabine A1 - Obrosov, Aleksei A1 - Dubovikov, Kirill T1 - Structural-phase surface composition of porous TiNi produced by SHS T2 - Materials Research Express N2 - The study aimed to characterize the structural-phase composition of the porous SHS TiNi surface explored by the GIXRD method. The surface layers at a depth of up to 100 nm mainly consist of amorphous nanocrystalline intermetallic oxycarbonitrides Ti₄Ni₂(O,N,C) with nonmetallic inclusions of different structural variants and routes of origin. Fine-porous alloys were synthesized at ignition temperatures of 450-480 °C. A distinct feature of the surface of crystalline phases therein was shown to be a low degree of crystallinity (up to 40%) and presence of multifarious glass and cermet phases evident as NiSi₂, NaAlSiO (SO₄), SiO₂, MgSi₂, and CaCO₃. Conversely, large-pore alloys ignited at temperatures of 280-330 °C have a higher degree of crystallinity (up to 70%). An individually selected GIXRD technique and precision structural phase analysis are capable to determine a set of other superficial nonmetallic and cermet phases reported as CaTiO₃, Si (P2O₇), CaSiO₃, MgAl₂O₄, TiNiAl, as well as the Ti₃SiC₂MAX phase. Y1 - 2019 UR - https://iopscience.iop.org/article/10.1088/2053-1591/ab4e32/pdf U6 - https://doi.org/10.1088/2053-1591/ab4e32 SN - 2053-1591 VL - 6 IS - 11 ER - TY - GEN A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Samad, Mohammed Abdul A1 - Touhami, Mohamed Zine A1 - Montagne, Alex A1 - Iost, Alain A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Preliminary investigation on the bio-tribocorrosion behavior of porous nanostructured β-type titanium based biomedical alloys T2 - Materials Letters N2 - The bio-tribocorrosion behavior of newly developed near β-types Ti-15Nb and Ti-15Mo alloys was investigated in Phosphate-Buffered Saline (PBS) under different loads. Open-Circuit Potential (OCP), friction coefficient, wear volume and wear rate were evaluated. The results revealed that Ti-15Nb alloy exhibited lower wear rate, lower friction coefficient and better corrosion resistance during tribocorrosion than the Ti-15Mo alloy. This can be attributed to the diffusion of Nb which increases the repassivation rate (formation of a protective layer) in the Ti-15Nb alloy. In contrast Ti-15Mo shows a significantly higher rate of chemical reaction. KW - Ti-15Mo KW - Ti-15Nb KW - Corrosion KW - Bio-tribocorrosion KW - Biomaterials Y1 - 2019 UR - https://www.sciencedirect.com/science/article/pii/S0167577X19313862 U6 - https://doi.org/10.1016/j.matlet.2019.126755 SN - 0167-577X VL - 257 ER - TY - GEN A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Touhami, Mohamed Zine A1 - Obrosov, Aleksei A1 - Weiß, Sabine A1 - Kashkarov, Egor B. A1 - Lider, Andrey M. A1 - Montagne, Alex A1 - Iost, Alain T1 - Enhanced Structural and Tribological Performance of Nanostructured Ti–15Nb Alloy for Biomedical Applications T2 - Results in Physics N2 - Low modulus β-type Ti-15Nb alloys were prepared by subjecting them to different sintering temperatures (800, 900, 1000 and 1100 °C) and their morphological and structural properties were evaluated. X-ray diffraction analysis was used for the morphological characterization which indicated that the mean pore and crystallite size continuously decreased with increasing sintering temperature to reach the lowest values of 41 nm and 27.5 nm at 1100 °C, respectively. Moreover, the higher sintering temperature resulted in higher relative density, greater hardness and young’s modulus of the Ti-15Nb alloys. Wear tests were conducted using a ball-on-plate type Oscillating tribometer, under different applied loads (2, 8 and 16 N) to evaluate their tribological characterization. The wear rate and friction coefficient were lower at higher sintering temperature. This enhancement in tribological properties was attributed to a grain refinement. The Ti-15Nb alloys sintered at 1100 °C showed the best tribological performance. KW - Tribological properties KW - Sintering KW - Biomaterial KW - β-Ti Alloys KW - Ti-15Nb alloys KW - Milling Y1 - 2019 UR - https://www.sciencedirect.com/science/article/pii/S2211379719300506 U6 - https://doi.org/10.1016/j.rinp.2019.102767 SN - 2211-3797 VL - 15 ER - TY - GEN A1 - Stendal, Johan Andreas A1 - Bambach, Markus A1 - Eisentraut, Mark A1 - Sizova, Irina A1 - Weiß, Sabine T1 - Applying Machine Learning to the Phenomenological Flow Stress Modeling of TNM-B1 T2 - Metals N2 - Data-driven or machine learning approaches are increasingly being used in material science and research. Specifically, machine learning has been implemented in the fields of materials discovery, prediction of phase diagrams and material modelling. In this work, the application of machine learning to the traditional phenomenological flow stress modelling of the titanium aluminide (TiAl) alloy TNM-B1 (Ti-43.5Al-4Nb-1Mo-0.1B) is investigated. Three model types were developed, analyzed and compared; a physics-based phenomenological model (PM) originally developed for steel by Cingara and McQueen, a purely data-driven machine learning model (MLM), and a hybrid model (HM), which uses characteristic points predicted by a learning algorithm as input for the phenomenological model. The same amount of data was used to both fit the PM and train the MLM and HM. The models were analyzed and compared based on the accuracy of their predictions, development and computing time, and their ability to predict on interpolated and extrapolated inputs. The results revealed that for the same amount of experimental data, the MLM was more accurate than the PM. In addition, the MLM was better able to capture the characteristic peak stress in the TNM-B1 the flow curves, and could be developed and computed faster. Furthermore, the MLM was able to make realistic predictions for inputs outside the experimental data used for training. The HM showed comparable accuracy to the PM for the experimental conditions. However, the HM was able to produce a better fit for input conditions outside the training data. KW - machine learning KW - phenomenological modeling KW - titanium aluminide KW - hot isothermal forging Y1 - 2019 UR - https://www.mdpi.com/2075-4701/9/2/220 U6 - https://doi.org/10.3390/met9020220 SN - 2075-4701 VL - 9 IS - 2 ER - TY - GEN A1 - Eisentraut, Mark A1 - Bolz, Sebastian A1 - Sizova, Irina A1 - Bambach, Markus A1 - Weiß, Sabine T1 - Development of a heat treatment strategy for the γ-TiAl based alloy TNM-B1 to increase the hot workability T2 - SN Applied Sciences Y1 - 2019 U6 - https://doi.org/10.1007/s42452-019-1563-4 SN - 2523-3963 SN - 2523-3971 VL - 1 IS - 11 ER - TY - GEN A1 - Stendal, Johan Andreas A1 - Eisentraut, Mark A1 - Sizova, Irina A1 - Bolz, Sebastian A1 - Bambach, Markus A1 - Weiß, Sabine T1 - Effect of heat treatment on the workability of hot isostatically pressed TNM-B1 T2 - AIP Conference Proceedings Y1 - 2019 SN - 978-0-7354-1847-9 U6 - https://doi.org/10.1063/1.5112544 VL - 2113 IS - 1 ER - TY - CHAP A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Abderrahim, Karima A1 - Samad, Mohammed Abdul A1 - Montagne, Alex A1 - Mejias, Alberto A1 - Iost, Alain A1 - Kossman, Stephania A1 - Chekalkin, Timofey A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Investigating the Effect of Sintering Temperature on Structural and Tribological Properties of a Nanostructured Ti–20Nb–13Zr Alloy for Biomedical Applications T2 - Characterization of Minerals, Metals, and Materials N2 - β-type Ti–20Nb–13Zr alloys with low Young’s modulus were prepared at different sintering temperatures (950, 1050, 1150, and 1250 °C). The morphological and structural characteristics of as-prepared samples were investigated by several methods. Wear tests were conducted using a ball-on-plate type oscillating tribometer under different applied loads (2, 10, and 20 N). The morphological characterization indicated that the mean pore and crystallite size continuously decreased with increasing sintering temperature to reach lowest values of 40 nm and 38 nm at 1250 °C, respectively. The relative density of the 1250 °C sintered sample was as high as 98.7%. Moreover, the higher sintering temperature resulted in higher relative density and closed porosity of the sample. Both the friction coefficient and wear rate were lower in the sample sintered at 1250 °C as compared to other samples. This enhancement in tribological properties was attributed to a closed porosity. KW - Ti-20Nb-13Zr KW - Nanobiomaterials KW - Tribological behaviour KW - Nanotribology KW - Sintering KW - Biomedical applications Y1 - 2020 SN - 978-3-030-36628-5 SN - 978-3-030-36627-8 U6 - https://doi.org/10.1007/978-3-030-36628-5_61 SN - 2367-1181 SN - 2367-1696 SP - 619 EP - 629 PB - Springer CY - Cham ER - TY - GEN A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Touhami, Mohamed Zine A1 - Hussien, Mohammed A. A1 - Montagne, Alex A1 - Mejias, Alberto A1 - Iost, Alain A1 - Kossman, Stephania A1 - Chekalkin, Timofey A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Effect of Sintering Temperature on Mechanical and Tribological Behavior of Ti–Ni Alloy for Biomedical Applications T2 - TMS 2020 149th Annual Meeting & Exhibition Supplemental Proceedings N2 - Ti–Ni powder compacts were prepared by mechanical alloying (MA), followed by hot isostatic pressing (HIP). Afterwards, the samples were sintered at different temperatures (950, 1050, 1150 and 1250 °C). Microhardness, density, crystallite size as well as microstrain of the sintered samples were measured and analyzed. Wear characteristics in phosphate-buffered saline (PBS) solution was tested under different applied loads of 2 N, 10 N, and 20 N, respectively. The results indicated that the crystallite size continuously decreases with increasing sintering temperature and reaches the lowest value of 31.3 nm at 1250 °C. The relative density of the sample sintered at 1250 °C is 98.0%. Moreover, the higher sintering temperatures lead to the higher relative density and the increase in hardness and young’s modulus of the sample. At the same time the friction coefficient and wear rate were lower for the samples sintered at 1250 °C. This improvement in friction and wear resistance is attributed to the grain size refinement. Ti–Ni sintered at 1250 °C showed good tribological performance under all test conditions. KW - Ti–Ni KW - Nanobiomaterials KW - Tribological behaviour KW - Sintering KW - Biomedical applications Y1 - 2020 SN - 978-3-030-36295-9 SN - 978-3-030-36296-6 U6 - https://doi.org/10.1007/978-3-030-36296-6_157 SN - 2367-1181 SN - 2367-1696 SP - 1701 EP - 1710 PB - Springer CY - Cham ER - TY - GEN A1 - Hezil, Naouel A1 - Fellah, Mamoun A1 - Montagne, Alex A1 - Iost, Alain A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Removal of Chromium (VI) from Water onto Activated Carbon by Adsorption in Dynamic Mode T2 - TMS 2020 149th Annual Meeting & Exhibition Supplemental Proceedings N2 - Hexavalent chromium pollution from industrial waste water is a serious problem as it can cause adverse effects on the environment. Several methods are used to reduce the harmful effects of this pollutant, especially physico-chemical methods, such as adsorption technology. The present study aims to remove Cr (VI) from industrial sources in a fixed-bed column of activated carbon. The experiments were carried out at natural pH and temperature with a flow rate (5, 10, and 20 mL/min) and bed height (3.5 cm). Breakthrough curves for feed concentrations (0.01, 0.03, and 0.05 mol/L) were investigated. The results indicated a marked decrease up to 99%. The value of the flow constant for the Thomas model decreased with the increase in the concentration of the incoming substance, but increased with the increase in the flow rate. KW - Hexavalent chromium KW - Activated carbon KW - Adsorption KW - Breakthrough curve KW - Fixed-bed column Y1 - 2020 SN - 978-3-030-36295-9 SN - 978-3-030-36296-6 U6 - https://doi.org/https://doi.org/10.1007/978-3-030-36296-6_80 SN - 2367-1181 SN - 2367-1696 SP - 855 EP - 863 PB - Springer CY - Cham ER - TY - GEN A1 - Evdokimov, Anton A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Obrosov, Aleksei A1 - Weiß, Sabine A1 - Michailov, Vesselin T1 - Thermomechanical laser welding simulation of dissimilar steel-aluminum overlap joints T2 - International Journal of Mechanical Sciences N2 - Mixing of steel and aluminum within the weld pool during keyhole laser welding results in a complex dissimilar microstructure, which in turn, initiates a shift in weld metal mechanical properties. In this study, a numerical model for computation of distortions in laser-welded dissimilar overlap joints (austenitic stainless steel 304 – 6082-T6 aluminum alloy), which considers properties of the mixed steel-aluminum weld metal was developed. The required yield strength, Young's modulus, and strain hardening exponent of the weld metal were experimentally determined using the indentation technique coupled with energy-dispersive X-ray spectroscopy. The designed material model calculates the weld elastic-plastic properties as a function of the aluminum concentration. The softening of the alloys in the heat-affected zone was determined by physical simulations and considered as a function of maximum temperature. Computed and measured distortions showed good agreement for various welding regimes with an average deviation of 18.4%. The sensitivity analyses indicated that the application of the developed weld material model significantly improves the accuracy of the thermomechanical simulations. Y1 - 2021 U6 - https://doi.org/10.1016/j.ijmecsci.2020.106019 SN - 1879-2162 VL - 190 ER - TY - GEN A1 - Baigonakova, Gulsharat A1 - Marchenko, Ekaterina A1 - Chekalkin, Timofey A1 - Kang, Ji-hoon A1 - Weiß, Sabine A1 - Obrosov, Aleksei T1 - Influence of Silver Addition on Structure, Martensite Transformations and Mechanical Properties of TiNi–Ag Alloy Wires for Biomedical Application T2 - Materials N2 - The microstructural and functional behavior of TiNi-based wires with a silver content of 0–1.5 at.% was evaluated. The concentration range for Ag doping determined for the TiNi wires with potential for the medical industry was 0–0.2 at.%. Microstructure analysis of TiNi wires with different silver contents at room temperature indicated a multiphase structural state. Various internal structures with tangled grain boundaries were formed by intense plastic deformation. The nanocrystalline structure and phase state of wire with the minimum silver content (0.1 at.% Ag) provide full shape recovery, the greatest reversible strain, and optimal strength and ductility. TiNi ingots with a high Ag content (0.5–1.5 at.%) cracked under minimum load due to excess silver that crystallized along the grain boundaries and broke cohesion bonds between the TiNi grains. KW - shape memory alloy KW - silver KW - doping KW - mechanical properties KW - nanostructured material KW - wire Y1 - 2020 UR - https://www.mdpi.com/1996-1944/13/21/4721 U6 - https://doi.org/10.3390/ma13214721 SN - 1996-1944 VL - 13 IS - 21 ER - TY - GEN A1 - Hazil, Naouel A1 - Fellah, Mamoun A1 - Montagne, Alex A1 - Iost, Alain A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Study of the photocatalytic degradation of Orange methyl dye in the presence of titanium dioxide T2 - La Troisième Conférence Méditerranéenne de la Biodiversité 2019 (BIODIV 2019) N2 - The use of photocatalytic techniques for water purification and wastewater treatment is very widespread, in our work we used TiO2 to photocatalyrate orange methyl (MO). In addition, the effects of some parameters on photodegradation of MO have been studied, such as the presence and / or absence of light (UV). The use of TiO2 showed a high MO degradation efficiency of up to 98%. The presence of H2O2 in the photocatalytic reaction may favor the photocatalytic degradation efficiencies. In addition, the experimental results have demonstrated an excellent rate of the order of 99%. KW - Titanium Dioxide KW - Photocatalytic Degradation Y1 - 2019 UR - http://ascob.net/files/abstract_book_biodiv2019_finale.pdf SP - 105 PB - L’ASCOB-SYRTIS CY - Hammamet, Tunisie ER - TY - GEN A1 - Prechavut, Ananya A1 - Weiß, Sabine T1 - Analyse der Korrosionsprodukte eines im CO2 Methanisierungsprozess verwendeten Edelstahlflansches aus 316L N2 - Die Weltklimakonferenz fordert eine massive Senkung der Treibhausgasemissionen mittels Abkehr von der Nutzung fossiler Brennstoffe hin zur Verwendung umweltverträglich hergestellter Energie. Da erneuerbare Energien aber bisher nicht durchweg bedarfsgerecht zur Verfügung stehen und schlecht speicherbar sind, besteht eine kurzfristige Lösungsmöglichkeit in Umwandlung, Speicherung und Wiederverwendung klimaschädlicher Verbrennungsgase. Eine effiziente Lösung zur Nutzung von CO2 ist dessen Umwandlung in ein speicherbares, zur Energieerzeugung nutzbares Gas. Mit der Methanisierung von CO2 kann eine erhebliche Reduzierung der Treibhausgasemissionen erreicht werden, wenn Methanschlupf vermieden wird. Bei dieser sogenannten Sabatier-Reaktion, die normalerweise bei 350°C bis 600°C stattfindet, reagiert Kohlendioxid mit Wasserstoff zu Methan. Als Reaktionsprodukte treten außer Methan und Wasser die Rest-Reaktanten sowie kleine Mengen an Verunreinigungen aus dem Verbrennungsprozess auf. Reaktionsbehälter und Leitungen bestehen üblicherweise aus Edelstahl. Durch hohe Umgebungs-temperatur und aggressive Umgebungsmedien kann auch bei dem normalerweise temperatur- und korrosionsbeständigen Werkstoff 316L Korrosion auftreten, Materialeigenschaften beeinflussen und zu Materialversagen führen. Zur Bewertung des Einflusses des CO2 Methanisierungs-Prozesses auf 316L wurde ein Methanisierungs-Reaktor im Labormaßstab nach der Nutzung demontiert und untersucht. In verschiedenen Bauteilen des Reaktors (Gaszuleitung, Gasaustritt, Reaktorsegment) wurden Korrosionsbeläge gefunden. Abhängig von ihrer Lage im Bauteil sind diese Korrosionsschichten sehr unterschiedlich aufgebaut. Mikrostruktur und Elementzusammensetzung der Schichten wurden mittels Rasterelektronenmikroskopie kombiniert mit energiedispersiver Röntgenspektroskopie analysiert. Während die Gaszuleitung nur moderaten Korrosionsangriff zeigt konnten im Bereich des Gasaustritts Spalt-, Kontakt- und Lochkorrosion nachgewiesen werden. Innerhalb der Korrosions¬schichten wurden drei Zonen (Mehrschichtenstruktur, Partikelansammlung und brüchiger Passivfilm) identifiziert. Die Mehrschichtzone setzt sich aus kolumnaren und granularen Strukturen zusammen, die Partikelansammlungen bestehen aus zylinderförmigen und kugelförmigen Partikeln. Die Elementzusammensetzung innerhalb der Korrosionsschichten lässt auf Kontaktkorrosion verursacht durch das Material der Dichtringe schließen. Y1 - 2020 UR - https://met2020.dgm.de/programm/?tx_dgmprogram_fullprogram%5Bsession%5D=9241&tx_dgmprogram_fullprogram%5Baction%5D=show&tx_dgmprogram_fullprogram%5Bcontroller%5D=Session&cHash=2c39b0ff319036dcd452cdf3debd6573 ER - TY - GEN A1 - Prechavut, Ananya A1 - Weiß, Sabine T1 - Corrosion Analysis of a 316L Stainless Steel Gas Outlet Sealed with a Copper Ring Used in the CO2 Methanation Process N2 - The central commitment of the 2015 World Climate Conference is to limit geothermal heating by massively reducing greenhouse gas emissions by decreasing the use of fossil fuels and promoting environmentally friendly energy. However, since renewable energies have so far not been available as required and are difficult to store, there is a short-term solution in the conversion, storage and reuse of climate-damaging combustion gases. An efficient solution for using CO2 is to convert it into a gas that can be stored and used to generate energy. With the so-called “power-to-gas technology”, a significant reduction in greenhouse gas emissions can be achieved by methanation of CO2 if methane slip is avoided. Methanation is a chemical reaction in which carbon dioxide reacts with hydrogen to methane. This transformation, which normally takes place at 350 ° C to 600 ° C, is also known as the Sabatier reaction. In addition to methane and water, the remaining reactants such as carbon dioxide, hydrogen, oxygen and nitrogen as well as small amounts of impurities from the combustion process, occur as reaction products. Reaction containers and lines are usually made of stainless steel. Due to high ambient temperature and aggressive ambient media, corrosion can also occur with the generally temperature and corrosion-resistant 316L material, influence material properties and lead to material failure. To assess the influence of the CO2 methanation process on 316L, a laboratory-scale methanation reactor was fractioned and examined after use. Corrosion deposits were found in various components of the reactor (gas supply line, gas outlet, reactor segment). Depending on their position within the component, these corrosion layers are structured very differently. Microstructure and element composition of the layers were analyzed using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. While the gas supply shows only moderate corrosion attack, crevice, contact- and pitting corrosion were detected in the corroded area of the gas outlet. Three zones (multilayer structure, particle accumulation and brittle passive film) were identified within the corrosion layers. The multi-layer zone is composed of columnar and granular structures, the particle accumulations consist of cylindrical and spherical particles. The element composition within the corrosion layers suggests contact corrosion caused by the material of the sealing rings. Y1 - 2020 UR - https://www.mse-congress.de/program/poster-session/?tx_dgmprogram_fullprogram%5Bsession%5D=9384&tx_dgmprogram_fullprogram%5Baction%5D=show&tx_dgmprogram_fullprogram%5Bcontroller%5D=Session&cHash=5069393772f53823bac5d5cde190c414 ER - TY - GEN A1 - Eisentraut, Mark A1 - Stendal, Johan Andreas A1 - Bolz, Sebastian A1 - Bambach, Markus A1 - Weiß, Sabine T1 - Applying a softening adapted acceleration to the hot deformation of TNM-B1 T2 - MRS Fall Meeting 2020 N2 - Hot isostatically forged TiAl turbine blades made of TNM-B1 are commercially used in aircraft engines, as they offer significantly lower weight than the traditional nickel-based blades while exhibiting similar strength. Like other TiAl alloys, TNM-B1 displays high peak stress followed by a strong softening behavior (i.e. stress reduction) during hot deformation. This softening can be used to accelerate the deformation process by reducing the processing time and in turn the costs for TNM-B1 parts. In order to avoid increased damage during the accelerated process, a pre-heat treatment (HT) for the hot isostatically pressed material (HIP) is required. To simulate the accelerated forming process, hot compression tests were performed with a DIL805A/D/T dilatometer from TA Instruments (New Castle, Delaware, USA) with different strain rates (0.0013, 0.005, 0.01 and 0.05) and temperatures (T=1150, 1175 and 1200°C). Deformation of the heat-treated state revealed lower flow stress (in both, peak stresses and steady state stresses) and fewer voids compared to the HIP state (Fig. 1.a). The compression test data were used to develop material and temperature specific strain rate profiles based on a material model. Subsequently, hot compression tests were performed with different strain rate profiles (starting strain rates 0.0013 and 0.0052) for the HIP and the HT state. The results were evaluated with regard to their microstructure, deformation, and damage behavior. A reduction of the processing time for all tested strain rates profiles by factors 2-3 could be achieved compared to constant strain rates. Furthermore, the results indicated that the deformation with strain rate profiles (compared to constant strain rates) did not significantly change the resulting microstructure or damage tolerance of the HT state. Y1 - 2020 UR - https://www.mrs.org/meetings-events/fall-meetings-exhibits/2020-mrs-spring-and-fall-meeting/call-for-papers/symposium-sessions-detail?code=F.SF07 ER - TY - GEN A1 - Morozova, Iuliia A1 - Obrosov, Aleksei A1 - Naumov, Anton A1 - Królicka, Aleksandra A1 - Golubev, Iurii A1 - Bokov, Dmitry O. A1 - Doynov, Nikolay A1 - Weiß, Sabine A1 - Michailov, Vesselin T1 - Impact of Impulses on Microstructural Evolution and Mechanical Performance of Al-Mg-Si Alloy Joined by Impulse Friction Stir Welding T2 - Materials N2 - Impulse Friction Stir Welding (IFSW) was utilized to join 6082–T6 alloy plates at various impulse frequencies. A distinctive feature of IFSW is the generation of mechanical impulses that enhances the forging action of the tool, and thereby, alters the weld microstructure. The microstructural evolution in the Stir Zone (SZ) with special focus on the strengthening precipitation behavior, and overall mechanical properties of the IFSW joints have been investigated. It was demonstrated that the strengthening β″ precipitates reprecipitated in the SZ of the IFSW joints during natural aging. In contrast, no precipitates were found in the SZ of the Friction Stir Welding (FSW) weld. Partial reversion of β″ after IFSW is supposed to occur due to more developed subgrain network and higher dislocation density introduced by impulses that accelerated precipitation kinetics. Dynamic recrystallisation was facilitated by impulses resulting in a fine, homogeneous structure. There was no significant difference between the microhardness in the SZ, tensile and yield strength of the FSW and IFSW joints. However, the application of impulses demonstrated the smoothing of the hardness reduction in the transition region at the advancing side. The shift of the fracture location from the Heat-Affected Zone (HAZ) by FSW to the SZ as well as higher elongation of the joints by IFSW of lower frequencies could be related to the grain refinement and the change of the grain orientation. KW - Al-Mg-Si alloy KW - impulse friction stir welding (IFSW) KW - precipitation KW - microstructure evolution KW - mechanical properties Y1 - 2021 UR - https://www.mdpi.com/1996-1944/14/2/347/htm U6 - https://doi.org/https://doi.org/10.3390/ma14020347 SN - 1996-1944 VL - 14 IS - 2 ER - TY - GEN A1 - Biedunkiewicz, Anna A1 - Figiel, Paweł A1 - Garbiec, Dariusz A1 - Obrosov, Aleksei A1 - Pawlyta, Mirosława A1 - Biedunkiewicz, Witold A1 - Pruss, Przemysław A1 - Rokosz, Krzysztof A1 - Wróbel, Rafał A1 - Raaen, Steinar A1 - Weiß, Sabine A1 - Bokov, Dmitry O. T1 - Influence of Elemental Carbon (EC) Coating Covering nc-(Ti,Mo)C Particles on the Microstructure and Properties of Titanium Matrix Composites Prepared by Reactive Spark Plasma Sintering T2 - Materials N2 - This paper describes the microstructure and properties of titanium-based composites obtained as a result of a reactive spark plasma sintering of a mixture of titanium and nanostructured (Ti,Mo)C-type carbide in a carbon shell. Composites with different ceramic addition mass percentage (10 and 20 wt %) were produced. Effect of content of elemental carbon covering nc-(Ti,Mo)C reinforcing phase particles on the microstructure, mechanical, tribological, and corrosion properties of the titanium-based composites was investigated. The microstructural evolution, mechanical properties, and tribological behavior of the Ti + (Ti,Mo)C/C composites were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), electron backscatter diffraction analysis (EBSD), X-ray photoelectron spectroscopy (XPS), 3D confocal laser scanning microscopy, nanoindentation, and ball-on-disk wear test. Moreover, corrosion resistance in a 3.5 wt % NaCl solution at RT were also investigated. It was found that the carbon content affected the tested properties. With the increase of carbon content from ca. 3 to 40 wt % in the (Ti,Mo)C/C reinforcing phase, an increase in the Young’s modulus, hardness, and fracture toughness of spark plasma sintered composites was observed. The results of abrasive and corrosive resistance tests were presented and compared with experimental data obtained for cp-Ti and Ti-6Al-4V alloy without the reinforcing phase. Moreover, it was found that an increase in the percentage of carbon increased the resistance to abrasive wear and to electrochemical corrosion of composites, measured by the relatively lower values of the friction coefficient and volume of wear and higher values of resistance polarization. This resistance results from the fact that a stable of TiO2 layer doped with MoO3 is formed on the surface of the composites. The results of experimental studies on the composites were compared with those obtained for cp-Ti and Ti-6Al-4V alloy without the reinforcing phase. KW - nanocomposites KW - TiMMCs KW - spark plasma sintering KW - (Ti,Mo)C/C KW - EBSD KW - fracture toughness Y1 - 2021 UR - https://www.mdpi.com/1996-1944/14/1/231 U6 - https://doi.org/https://doi.org/10.3390/ma14010231 SN - 1996-1944 VL - 14 IS - 1 ER - TY - GEN A1 - Stendal, Johan Andreas A1 - Eisentraut, Mark A1 - Sizova, Irina A1 - Bolz, Sebastian A1 - Weiß, Sabine A1 - Bambach, Markus T1 - Accelerated hot deformation and heat treatment of the TiAl alloy TNM-B1 for enhanced hot workability and controlled damage T2 - Journal of Materials Processing Technology Y1 - 2021 U6 - https://doi.org/10.1016/j.jmatprotec.2020.116999 SN - 0924-0136 VL - Vol. 291 ER - TY - GEN A1 - Fouzia, Hammadi A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Aissani, Linda A1 - Mimanne, Goussem A1 - Mechachti, Said A1 - Samad, Mohammed Abdul A1 - Montagne, Alex A1 - Iost, Alain A1 - Weiß, Sabine A1 - Obrosov, Aleksei T1 - The effect of milling time on the microstructure and mechanical properties of Ti-6Al-4Fe alloys T2 - Materials Today Communications N2 - Replacement of toxic and expensive vanadium (V) in medical grade titanium alloys with cheaper and non-toxic elements such as iron (Fe) or niobium (Nb), is an important step forward in developing safer and less expensive biomaterials. Evaluating the effect of different process parameters such as the milling time on the properties of these newly developed alloys helps in understanding and controlling their behavior. Hence, in this study, the influence of ball-milling duration (2, 6, 8, 12 and 18 h) on crystalline structure, phase evolution, densification, and mechanical characteristics of biomedical nanocrystalline Ti-6Al-4Fe (wt. %) alloys is investigated. X-ray diffraction (XRD) confirmed that after 6 h of milling, aluminum (Al) and Fe completely dissolved into Ti matrix to form a solid solution of Ti (Al, Fe). XRD further revealed that the crystallite size decreased from 56 to 30 nm and the micro-strain increased with an increase in milling time. A decrease in porosity along with an increase in density is also observed for the alloys with increasing milling time. Moreover, the values of porosity obtained for the developed Ti-6Al-4Fe alloys ranged from 1 to 12 %, which is comparable to the porosity of one of the cortical bones making it a potential candidate for bone replacements. Microhardness measurements showed that the hardness of the Ti-6Al-4Fe alloys was greater than the hardness of the conventional Ti-6Al-4V alloys. It was observed that the Ti-6Al-4Fe alloy fabricated with the powders milled for 2 h showed the lowest value of Young’s Modulus. Milling time also had a significant effect on the surface roughness of the alloy samples, which showed a decreasing trend with increasing milling times. KW - Ti-based alloys KW - Microstructure KW - Mechanical properties KW - Ball-milling KW - Biomaterials KW - Milling time Y1 - 2021 UR - https://www.sciencedirect.com/science/article/abs/pii/S2352492821004207#! U6 - https://doi.org/10.1016/j.mtcomm.2021.102428 SN - 2352-4928 VL - 27 ER - TY - GEN A1 - Grudinin, V. A. A1 - Sidelev, D. V. A1 - Bleykher, G. A. A1 - Yuriev, Yu N. A1 - Krivobokov, V. P. A1 - Berlin, E. V. A1 - Grigoriev, V. Yu A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Hot target magnetron sputtering enhanced by RF-ICP source for CrNx coatings deposition T2 - Vacuum N2 - This article describes hot Cr target magnetron sputtering enhanced by a radio-frequency inductively coupled plasma (RF-ICP) source in an Ar + N2 atmosphere. Optical emission spectroscopy revealed an opportunity to perform magnetron sputtering in an inert (Ar) atmosphere, while the CrNx coating can be deposited on a substrate in a chemically reactive atmosphere formed by the RF-ICP source. High stability and repeatability of deposition process were observed, and the deposition rate of the CrNx coatings increased from 106 to 127 nm/min as N2 flow rate rose. The power of the RF-ICP source and the N2 flow rate can be used to tailor and control deposition conditions. The XRD and WDS measurements showed the effect of deposition conditions on the crystal structure and elemental composition of CrNx coatings. It was found that the change of substrate bias, RF-ICP source power and N2 flow rate result in variation of coating stoichiometry from pure Cr to CrN. KW - CrN coatings KW - Hot target KW - Magnetron sputtering KW - High-rate deposition KW - RF inductively Coupled plasma Y1 - 2021 UR - https://www.sciencedirect.com/science/article/pii/S0042207X21003523?via%3Dihub#! U6 - https://doi.org/10.1016/j.vacuum.2021.110400 SN - 0042-207X VL - 191 ER - TY - GEN A1 - Krzywiński, Kamil A1 - Sadowski, Łukasz A1 - Stefaniuk, Damian A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Engineering and Manufacturing Technology of Green Epoxy Resin Coatings Modified with Recycled Fine Aggregates T2 - International Journal of Precision Engineering and Manufacturing-Green Technology N2 - Nowadays, the recycled fine aggregate sourced from construction and demolition waste is not frequently used in manufacturing of epoxy resin coatings. Therefore, the main novelty of the article is to prepare green epoxy resin coatings modified with recycled fine aggregate in a replacement ratio of natural fine aggregate ranged from 20 to 100%. The microstructural properties of the aggregates and epoxy resin were analyzed using micro-computed tomography, scanning electron microscopy and nanoindentation. The macroscopic mechanical properties were examined using pull-off strength tests. The highest improvement of the mechanical properties was observed for epoxy resin coatings modified with 20% of natural fine aggregate and 80% of recycled fine aggregate. It has been found that even 100% of natural fine aggregate can be successfully replaced using the recycled fine aggregate with consequent improvement of the pull-off strength of analyzed epoxy resin coatings. In order to confirm the assumptions resulting from the conducted research, an original analytical and numerical failure model proved the superior behavior of modified coating was developed. KW - Manufacturing KW - Wear KW - Composite KW - Epoxy resin coating KW - Recycled aggregate KW - Green material Y1 - 2022 UR - https://link.springer.com/article/10.1007/s40684-021-00377-w U6 - https://doi.org/10.1007/s40684-021-00377-w SN - 2198-0810 VL - 9 IS - 1 SP - 253 EP - 271 ER - TY - GEN A1 - Aissani, Linda A1 - Fellah, Mamoun A1 - Chadli, Abdel Hakim A1 - Samad, Mohammed Abdul A1 - Cheriet, Abderrahmane A1 - Salhi, Faiza A1 - Nouveau, Corinne A1 - Weiß, Sabine A1 - Obrosov, Aleksei A1 - Alhussein, Akram T1 - Investigating the effect of nitrogen on the structural and tribo-mechanical behavior of vanadium nitride thin films deposited using R.F. magnetron sputtering T2 - Journal of Materials Science N2 - Magnetron sputtering is one of the most commonly used deposition techniques, which has received considerable attention in industrial applications. In particular, owing to its compatibility with conventional fabrication processes, it can produce and fabricate high-quality dense thin films of a wide range of materials. In the present study, nitrogen (N) was combined with pure vanadium in order to form binary nitride to improve its mechanical and tribological performance. To evaluate the influence of nitrogen on the structure of the as-deposited vanadium nitride (VN) coatings, the following techniques were used: XPS, XRD, SEM, AFM and optical profilometry. The residual stresses were determined by the curvature method using Stoney’s formula. The hardness and Young’s modulus were obtained by nanoindentation measurements. The friction behavior and wear characteristics of the films were evaluated by using a ball-on-disk tribometer. The obtained results showed that the N/V ratio increased with increasing the N2 flow rate while the deposition rate decreased. The preferred orientation was changed from (200) to (111) as the N2 flow rate increased with the presence of V–N and V–O binding energies as confirmed by XPS analysis. The nitrogen addition resulted in a columnar morphology and a fine structure with fine surface roughness. The VN thin film containing 49.5 at.% of nitrogen showed the best performance: highest mechanical properties (hardness = 25 GPa), lowest friction coefficient (μ = 0.37) and lowest wear rate (Ws = 2.72 × 10−5 mm3N−1 m−1). A good correlation between the film microstructure, crystallite size, residual stress and mechanical and tribological properties was observed. Y1 - 2021 U6 - https://doi.org/10.1007/s10853-021-06393-0 SN - 1573-4803 SN - 0022-2461 VL - 56 IS - 30 SP - 17319 EP - 17336 ER - TY - GEN A1 - Shapovalov, Oleg A1 - Shapovalova, Mariia A1 - Ossenbrink, Ralf A1 - Heckel, Thomas A1 - Michailov, Vesselin A1 - Weiß, Sabine A1 - Gaal, Mate T1 - Verbessern der Korrosionsbeständigkeit eines hochtemperaturbeständigen Ultraschalldämpfungskörpers mittels Laserstrahl-Auftragschweißen T2 - DVS Berichte 2021 N2 - Während in einem konventionellen Ultraschallprüfkopf ein Kunststoffdämpfungskörper mit Kleber oder Öl an einen Piezoschwinger angekoppelt ist, werden als Hochtemperaturlösung feinporöse sintermetallische Dämpfungsmaterialien mit einer Flüssigglasankopplung eingesetzt. Um dabei das Sintermetall vor dem korrosiven Angriff der Glasschmelze zu schützten, wird am Dämpfungskörper gegenwärtig Gold- oder Platinfolie zeit- und kostenaufwendig appliziert. In der aktuellen Arbeit wurde eine Methode zum Korrosionsschutz der sintermetallischen Oberfläche aus rostfreiem Stahl mittels Laser-Pulverauftragschweißen entwickelt. Im Laufe einer Schweißparameterstudie auf dem Substratmaterial aus massivem rostfreiem Stahl wurde die Eignung unterschiedlicher Auftragsmaterialien auf Nickel- und Kobaltbasis untersucht. Dabei wurde zunächst der Einfluss verschiedener Schweißparameter wie Laserleistung, Vorschubgeschwindigkeit und Pulvermenge auf die Auftragsqualität (Nahtform, Vermischungsgrad, Porosität) metallografisch bewertet. Anschließend wurden die aufgetragenen Schichten hinsichtlich ihrer Korrosionsbeständigkeit getestet. Der Kontakt mit einer flüssigen Glasmischung bei 500 °C hat bei keiner der beschichteten Proben sichtbare Korrosionswirkung gezeigt. Als Resultat der Schweißparameterstudie haben sich besonders die nickelbasierten Pulver als gut geeignete Materialien für den Prozess gezeigt. Die identifizierten Schweißparameter wurden im nächsten Schritt erfolgreich an das sintermetallische Substrat angepasst. Y1 - 2021 UR - https://www.dvs-ev.de/call4papers/abstract.cfm?vid=109&pid=7032 SN - 978-3-96144-147-1 SP - 370 EP - 377 PB - DVS Media GmbH CY - Düsseldorf ER - TY - GEN A1 - Ermilova, Evgeniia A1 - Nikitin, Alexander A1 - Weiß, Sabine ED - Daehn, Glenn ED - Cao, Jian ED - Kinsey, Brad ED - Tekkaya, A. Erman ED - Vivek, Anupam ED - Yoshida, Yoshinori T1 - The Local Strain Evolution for Structured Sheet Metals During Uniaxial Deformation T2 - Forming the Future : Proceedings of the 13th International Conference on the Technology of Plasticity N2 - Structured materials can be progressive alternatives to commonly used flat sheets because of their higher bending stiffness and stability compared to flat sheet metals, made of the same alloy. The application of sheet metals requires accurate information regarding their strength and deformation behavior. Such data are not commonly available and have to be measured by specific test setups and implementation of tests. The aim of this work is to obtain new knowledge about deformation mechanisms of structured sheet metals. Structured sheet metals (SSM) made of conventional deep-drawing steel DC04 were investigated by means of tensile tests. The influence of the structure type arrangement on the deformation behavior was analyzed. The evolution of local strains was analyzed by means of strain gauge measurements as well as 3D-displacement measurements with an ARAMIS highresolution camera system. Local orientation changes in different structural elements were measured using the electron backscatter diffraction technique. KW - structured sheet metals, ssm, tensile test, ARAMIS, strain gauge, EBSD, REM, electron microscopy, DC04 steel Y1 - 2021 SN - 978-3-030-75381-8 SN - 978-3-030-75380-1 SN - 978-3-030-75383-2 U6 - https://doi.org/10.1007/978-3-030-75381-8_143 SN - 2367-1696 SP - 1701 EP - 1711 PB - Springer, Cham ET - 1 ER - TY - GEN A1 - Emdadi, Aliakbar A1 - Bolz, Sebastian A1 - Buhl, Johannes A1 - Weiß, Sabine A1 - Bambach, Markus T1 - Laser Powder Bed Fusion Additive Manufacturing of Fe3Al-1.5Ta Iron Aluminide with Strengthening Laves Phase T2 - Metals Y1 - 2022 U6 - https://doi.org/10.3390/met12060997 SN - 2075-4701 VL - 12 IS - 6 ER - TY - GEN A1 - Shapovalov, Oleg A1 - Heckel, Thomas A1 - Gaal, Mate A1 - Weiß, Sabine T1 - External Acoustical Damping on a Metallic Angle Wedge in a High Temperature Resistant Ultrasonic Probe T2 - Acoustics Australia N2 - Ultrasonic probes for high-temperature applications are provided with metallic wedges, which can withstand the contact with the high temperature of the inspected structure. The ultrasonic signal travels within the wedge and gets reflected from its boundaries, causing interference signals called “ghost echoes”. The current work presents an investigation of the additional damping effect provided by porous sintered metal plates applied onto the surface of the wedge. In particular, the study evaluates the effect of damping plate thickness on the interference signal level at different transmission frequencies. Damping plates made of sintered metal SIKA-R 15 AX were attached to a wedge prototype made of steel 1.4301. The study revealed, that the most effective thickness of damping plates in the selected frequency interval of 1 to 4 MHz is equal to 4 mm. The evaluation of the interference signal has shown that the application of such damping plates to the wedge surface contributes to an additional attenuation of an interference signal of 10 to 30 dB after 500 µs of signal propagation. KW - Ultrasonic Testing KW - High temperature KW - Acoustical damping KW - Angle wedge KW - Ultrasonic probe Y1 - 2022 UR - https://link.springer.com/article/10.1007/s40857-022-00270-9 U6 - https://doi.org/10.1007/s40857-022-00270-9 SN - 1839-2571 VL - 50 IS - 3 SP - 343 EP - 353 ER - TY - GEN A1 - Morozova, Iuliia A1 - Kehm, Christian A1 - Obrosov, Aleksei A1 - Yang, Yitong A1 - Miah, Kamal Uddin Mohammad A1 - Uludintceva, Elena A1 - Fritzsche, Sebastian A1 - Weiß, Sabine A1 - Michailov, Vesselin T1 - On the Heat Treatment of Selective-Laser-Melted 316L T2 - Journal of Materials Engineering and Performance N2 - The effect of heat treatment at various temperatures (650, 850, 1050, and 1100°C) and dwell times (10 min and 1 h) on the metallurgical and microstructural evolution as well as on the related tensile properties of stainless steel 316L processed by selective laser melting (SLM) has been systematically evaluated. The metallurgical and microstructural features such as defects, stability of the columnar–cellular structure and substructure, second phase particles, and phase transformation imparted by SLM and heat treatment have been discussed. It has been shown that the processing conditions specific to SLM significantly alter the kinetics of phase evolution compared to standard welding techniques which affects the accuracy of the prediction. The influence of these characteristics on tensile properties and hardness was elucidated. It was disclosed that with increasing heat treatment temperature there was a gradual increase in elongation but a decrease in strength related to the dislocation density and the development of the microstructure. KW - 316L KW - grain structure KW - phase evolution KW - SLM KW - tensile properties Y1 - 2023 U6 - https://doi.org/10.1007/s11665-022-07404-0 SN - 1544-1024 VL - 32 (2023) IS - 10 SP - 4295 EP - 4305 ER - TY - GEN A1 - Morozova, Iuliia A1 - Królicka, Aleksandra A1 - Obrosov, Aleksei A1 - Yang, Yitong A1 - Doynov, Nikolay A1 - Weiß, Sabine A1 - Michailov, Vesselin T1 - Precipitation phenomena in impulse friction stir welded 2024 aluminium alloy T2 - Materials Science and Engineering: A N2 - Microhardness variations across the friction stir welded (FSW) and impulse friction stir welded (IFSW) AA2024–T351 joints have been elucidated by the transformations of the S–Al2CuMg phase with a special focus on a distinguished hardness peak within the heat-affected zone (HAZ) of the impulse welds. The increase in hardness within the stir zone (SZ) originated from the partial re-precipitation of the initial Guinier-Preston-Bagaryatsky zones (GPB) and metastable S needles, previously dissolved.) Formation and growth of stable S precipitates via coalescence accounted for the softening through the thermo-mechanically affected zone (TMAZ). The peak strengthening within the HAZ of the IFSW joints was mainly caused by the dense needle-shaped S particles, which can be explained by a mutual influence of the process specific temperature and strain cycles. Dislocations and subgrain boundaries introduced to the material due to plastic deformation facilitated the nucleation of strengthening S precipitates in the HAZ. It demonstrates that the impact of deformation should be considered by the characterization of the precipitation development in the HAZ. KW - AA2024 KW - impulse friction stir welding KW - microhardness KW - s precipitation KW - thermal cycle KW - deformation Y1 - 2022 U6 - https://doi.org/10.1016/j.msea.2022.143617 SN - 0921-5093 SP - 1 EP - 11 ER - TY - GEN A1 - Figiel, Paweł A1 - Biedunkiewicz, Anna A1 - Jach, Katarzyna A1 - Obrosov, Aleksei A1 - Garbiec, Dariusz A1 - Bik, Maciej A1 - Sitarz, Maciej A1 - Kucia, Zofia A1 - Pawlyta, Mirosława A1 - Weiß, Sabine T1 - Ti-Mo-xTiC composites manufactured by U-FAST reactive sintering T2 - International Journal of Refractory Metals and Hard Materials N2 - The paper presents the characteristics of Ti-Mo-xTiC composites manufactured under experimentally selected conditions using the upgraded field-assisted sintering technique (U-FAST). Mixtures of microstructural titanium powders and nc-Ti0.9Mo0.1C/C carbide powders protected from oxidation by a carbon shell were subjected to sintering. The powders with nc-Ti0.9Mo0.1C/C contents of 10 and 20 wt% were used. The content of carbon forming the carbon shell was approximately 3 or 40 wt%. Composites with near full density were reinforced with titanium carbides in a Ti-Mo matrix. The composites with the highest content of reinforcing phase are characterized by the highest values of hardness, Young's modulus and wear resistance. Although the hardness of these composites is similar to that of ceramics, their nature is not brittle. Despite the high value of the Young's modulus, the addition of hard particles of the reinforcing phase to the titanium matrix significantly increases the values of the H/E ratio of the composites compared to the reference samples of cp-Ti and Ti6Al4V. A comparison of the research results for the composites with the highest share of titanium carbides showed that lowering the sintering temperature from 1300 to 1150 °C resulted in the inhibition of grain growth, a reduction in composite heterogeneity, composite roughness and hardness as well as a rise in the Young's modulus. An increase in the sintering temperature from 1150 to 1300 °C contributed to the higher high angle grain boundaries (HAGB) content. KW - TiMMCs KW - SPS KW - EBSD KW - Nanoindentation KW - Wear Y1 - 2022 UR - https://www.sciencedirect.com/science/article/pii/S0263436822001846#! U6 - https://doi.org/10.1016/j.ijrmhm.2022.105960 SN - 0263-4368 IS - 108 SP - 1 EP - 14 ER - TY - GEN A1 - Petkov, Nikolay A1 - Bakalova, Totka A1 - Obrosov, Aleksei A1 - Kashkarov, Egor B. A1 - Kormunda, Martin A1 - Kejzlar, Pavel A1 - Bahchedzhiev, Hristo A1 - Dadourek, Karel A1 - Weiß, Sabine T1 - Structural, mechanical, and tribological properties of CrCN coatings obtained by cathodic arc physical vapour deposition technology at different CH4/N2 gas ratio T2 - Thin Solid Films N2 - Chromium carbonitride coatings were deposited by cathodic arc physical vapor deposition technology at a temperature of 300 °C, as were used the reactive gasses CH4 and N2. The structural analysis of the CrN coating showed a polycrystalline structure with mixed CrN and Cr2N phases. All studied coatings, including the CrC exhibits fcc structure. The phases were confirmed by X-ray photoelectron spectroscopy measurements where a surface oxidation was also detected. The increase of the CH4 gas flow during the deposition process leads to a parabolic trend with the highest hardness of 33.5 GPa for the coating deposited at CH4 / N2 = 0.53. At the same time the lowest coefficient of friction for both counterparts Al2O3 and ZrO2 (0.28 and 0.26, respectively) were measured at CH4 / N2 = 1.86. The tribological tests reveal that the wear of the coatings increases with an increasing CH4 flow rate, whereas the coefficient of friction decreases. This observed contradiction is explained by a phenomenon described as the effect of Rebinder. KW - Chromium carbonitride KW - Cathodic arc deposition KW - X-ray diffraction KW - X-ray photoelectron spectroscopy KW - Mechanical properties KW - Wear Y1 - 2023 UR - https://www.sciencedirect.com/science/article/pii/S0040609022005715 U6 - https://doi.org/10.1016/j.tsf.2022.139669 SN - 1879-2731 VL - 766 ER - TY - GEN A1 - Grudinin, V. A. A1 - Bleykher, G. A. A1 - Krivobokov, V. P. A1 - Semyonov, O. V. A1 - Obrosov, Aleksei A1 - Weiß, Sabine A1 - Sidelev, D. V. T1 - Hot target magnetron sputtering enhanced by RF-ICP source: Microstructure and functional properties of CrNx coatings T2 - Vacuum N2 - CrNx coatings were deposited at high rates (100–130 nm/min) using hot Cr target magnetron sputtering enhanced by a radio-frequency inductively coupled plasma (RF-ICP) source in an Ar + N2 atmosphere. Besides separation of inert and reactive atmosphere, the RF-ICP source can be an effective tool for ion assistance in case of coating growth and to tailor film parameters. The effects of nitrogen flow rate and substrate bias potential on microstructure and functional properties of the CrNx coatings were investigated. An increase in nitrogen flow rate favored the formation of a looser microstructure of the coatings, while substrate biasing had the opposite effect. The functional properties were strongly dependent on the phase composition of the CrNx coatings. The change in coating microstructure significantly affected hardness, elastic modulus, adhesion, friction coefficients and corrosion resistance. The results indicated that ion assistance can be a key feature for regulating functional properties in the considered type of coating deposition. Cr2N and CrN compound coatings with high hardness (∼20 GPa) and low corrosion current density (icorr ∼ 3–5·10−9 A/cm2) in a 3.5 wt% NaCl solution were obtained by high-rate deposition. KW - CrN KW - Coatings KW - Hot target KW - Magnetron sputtering KW - High-rate deposition KW - RF-ICP Y1 - 2022 UR - https://www.sciencedirect.com/science/article/pii/S0042207X2200152X U6 - https://doi.org/10.1016/j.vacuum.2022.111020 SN - 1879-2715 VL - 200 ER - TY - GEN A1 - Alontseva, Darya A1 - Safarova (Yantsen), Yuliya A1 - Voinarovych, Sergii A1 - Obrosov, Aleksei A1 - Yamanoglu, Ridvan A1 - Khoshnaw, Fuad A1 - Yavuz, Hasan Ismail A1 - Nessipbekova, Assem A1 - Syzdykova, Aizhan A1 - Azamatov, Bagdat A1 - Khozhanov, Alexandr A1 - Weiß, Sabine T1 - Biocompatibility and Corrosion of Microplasma-Sprayed Titanium and Tantalum Coatings versus Titanium Alloy T2 - Coatings N2 - This study investigates the in vitro biocompatibility, corrosion resistance, and adhesion strength of a gas abrasive-treated Ti6Al4V alloy, alongside microplasma-sprayed titanium and tantalum coatings. Employing a novel approach in selecting microplasma spray parameters, this study successfully engineers coatings with tailored porosity, roughness, and over 20% porosity with pore sizes up to 200 μm, aiming to enhance bone in-growth and implant integration. This study introduces an innovative methodology for quantifying surface roughness using laser electron microscopy and scanning electron microscopy, facilitating detailed morphological analysis of both the substrate and coatings. Extensive evaluations, including tests for in vitro biocompatibility, corrosion resistance, and adhesive strength, revealed that all three materials are biocompatible, with tantalum coatings exhibiting superior cell proliferation and osteogenic differentiation, as well as the highest corrosion resistance. Titanium coatings followed closely, demonstrating favorable osteogenic properties and enhanced roughness, which is crucial for cell behavior and attachment. These coatings also displayed superior tensile adhesive strengths (27.6 ± 0.9 MPa for Ti and 28.0 ± 4.9 MPa for Ta), surpassing the ISO 13179-1 standard and indicating a robust bond with the substrate. Our findings offer significant advancements in biomaterials for medical implants, introducing microplasma spraying as a versatile tool for customizing implant coatings, particularly emphasizing the superior performance of tantalum coatings in terms of biocompatibility, osteogenic potential, and corrosion resistance. This suggests that tantalum coatings are a promising alternative for enhancing the performance of metal implants, especially in applications demanding high biocompatibility and corrosion resistance. KW - biocompatible coatings KW - in vitro test KW - corrosion resistance KW - microplasma spraying (MPS) KW - medical implants KW - coating techniques Y1 - 2024 UR - https://www.mdpi.com/2079-6412/14/2/206 U6 - https://doi.org/10.3390/coatings14020206 SN - 2079-6412 VL - 14 IS - 2 ER - TY - GEN A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Bouras, Dikra A1 - Bouchareb, Nabila A1 - Larios, Alejandro Perez A1 - Obrosov, Aleksei A1 - El-Hiti, Gamal A. A1 - Weiß, Sabine T1 - Investigating the effect of Zr content on electrochemical and tribological properties of newly developed near β-type Ti-alloys (Ti–25Nb-xZr) for biomedical applications T2 - Journal of Science: Advanced Materials and Devices N2 - In order to create alloys with exceptional properties for orthopedic uses, this study focuses on the impact of zirconium (Zr) content on the structural, electrochemical, and tribological qualities of nanostructured Ti–25Nb-xZr [x = 5, 10, 15, 20, 25, and 30 atomic (at.) %] alloys. The structural evolution was investigated using XRD and SEM techniques. The mechanical characteristics of the produced alloys, including Vickers hardness and Young's modulus, were measured. In addition, the corrosion tests were performed using the OCP, EIS, and PD methods in Ringer's solution within the independent pH range at 37 °C. A ball-on-disc tribometer was used to investigate the tribological behavior of the alloys under various loads and wet conditions using the Ringer solution. It has been verified that Zr content (at. %) in the alloys had an impact on their morphologies, structural evolution, and mechanical characteristics. According to the morphological analysis, the particle and crystallite size decreases with increasing Zr content. Young's modulus and Vickers hardness show the same tendency. The EIS data demonstrated that a single passive film formed on the alloy surfaces, and the addition of Zr enhanced the corrosion resistance of the passive films. The polarization curves demonstrate that the alloys had low corrosion current densities and large passive areas without the passive films disintegrating. Likewise, the inclusion of Zr resulted in a reduction in the corrosion and passive current densities values. All of these results suggested that the titanium alloys exhibit a more noble electrochemical activity caused by Zr. From the tribological perspective, it was found that the friction coefficient of the alloys reduced with increasing Zr content. KW - Ti-Nb-Zr alloys KW - Nanobiomaterials KW - Tribological behavior KW - Corrosion KW - Ringer's solution KW - Biomedical applications Y1 - 2024 UR - https://www.sciencedirect.com/science/article/pii/S2468217924000261 U6 - https://doi.org/10.1016/j.jsamd.2024.100695 SN - 2468-2179 ER - TY - GEN A1 - Fellah, Mamoun A1 - Bouchareb, Nabila A1 - Hezil, Naouel A1 - Merah, Neçar A1 - Alashkar, Yasser A1 - Imran, Mohd A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Electrochemical analysis of mechanically alloyed Ti50%-Ni50% alloy for bone implants use T2 - Journal of Alloys and Compounds N2 - The corrosion resistance of an implant material is an essential element of its biocompatibility. This research focuses on studying the effect of grinding/milling time on the corrosion behavior of the mechanically alloyed Ti50 %-Ni50 % (at%) alloy, for bone implant use, at varying milling times of 2, 6, 12, and 18 h. The powder particles' size, shape, and homogeneous chemical content were examined employing scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The alloyed particles' structural characteristics were determined by X-ray diffraction (XRD). Moreover, the characterization of the electrochemical properties was performed utilizing open-circuit potential (OCP) measurement, the Potentiodynamic Polarization (PD), and the Electrochemical Impedance Spectroscopy (EIS) technique. Electrochemical tests were conducted in physiological mediums simulating the human body: Hank's solution. The results revealed that; as the grinding time increased the crystallite size reduced from 57 nm to 29 nm, whereas the lattice parameters increased slightly from 3.18 to 3.22 Å, while the microstrain increased from 0.32 % to 0.99 %. Moreover, the hardness and Young's Modulus increased by about 70 and 16 %, respectively with milling period going from 2 to 18 h. The findings of the electrochemical test demonstrated that as milling progressed, corrosion resistance increased. The evolution of OCP curves as a function of the duration of immersions indicated that OCP increased with the duration of immersion up to 2500 s; this is due to a stable passive layer that has formed on the samples' surface. The results of potentiodynamic polarization curves revealed that both corrosion current density (icorr) and corrosion rate (CR) decreased reaching a value of 3.6945E-07 A/cm2 and 0.0074722 mm/year, respectively, at longer milling time (18 h). While, corrosion potential (Ecorr) increased from −0.51255 V/SCE to −0.29997 V/SCE with increasing grinding time. Additionally, the EIS data indicated that the resistance of the passive film increased with increasing milling times. The samples of Ti50-Ni50 produced at longer milling time exhibited excellent corrosion resistance due to the formation of a stable passive film which makes them useful for bone implants. KW - Ti-Ni alloys KW - Biomaterials KW - Mechanical alloying KW - Nanomaterial KW - Corrosion behavior KW - Electrochemical impedance spectroscopy Y1 - 2025 U6 - https://doi.org/https://doi.org/10.1016/j.jallcom.2024.178046 SN - 1873-4669 IS - 1010 SP - 1 EP - 13 ER - TY - GEN A1 - Alontseva, Darya A1 - Safarova (Yantsen), Yuliya A1 - Voinarovych, Sergii A1 - Obrosov, Aleksei A1 - Yamanoglu, Ridvan A1 - Khoshnaw, Fuad A1 - Nessipbekova, Assem A1 - Syzdykova, Aizhan A1 - Yavuz, Hasan Ismail A1 - Kaliuzhnyi, Sergii A1 - Krasavin, Alexander A1 - Azamatov, Bagdat A1 - Khozhanov, Alexandr A1 - Olzhayev, Farkhad A1 - Weiß, Sabine T1 - Microplasma-Sprayed Titanium and Hydroxyapatite Coatings on Ti6Al4V Alloy: in vitro Biocompatibility and Corrosion Resistance: Part I T2 - Johnson Matthey Technology Review N2 - This two-part paper investigates the bioactivity and mechanical properties of coatings applied to Ti6Al4V, a common titanium alloy used in endoprosthetic implants. Coatings made from hydroxyapatite (HA) powder and commercially pure titanium (CP-Ti) wires were applied using microplasma spraying. The study focuses on the responses of rat mesenchymal stem cells (MSCs), which are essential for bone healing, to these coatings. Part I shows how adjusting the microplasma spraying process allows coatings with varying porosity and surface roughness to be achieved. KW - Endoprosthesis implants KW - Biocompatible coatings KW - Porosity KW - Surface roughness KW - In vitro test KW - Elastic modulus Y1 - 2025 UR - https://technology.matthey.com/content/journals/10.1595/205651325X17201903387613 U6 - https://doi.org/10.1595/205651325X17201903387613 VL - 69 IS - 1 SP - 45 EP - 58 ER - TY - GEN A1 - Alontseva, Darya A1 - Safarova (Yantsen), Yuliya A1 - Voinarovych, Sergii A1 - Obrosov, Aleksei A1 - Yamanoglu, Ridvan A1 - Khoshnaw, Fuad A1 - Nessipbekova, Assem A1 - Syzdykova, Aizhan A1 - Yavuz, Hasan Ismail A1 - Kaliuzhnyi, Sergii A1 - Krasavin, Alexander A1 - Azamatov, Bagdat A1 - Khozhanov, Alexandr A1 - Olzhayev, Farkhad A1 - Weiß, Sabine T1 - Microplasma-sprayed titanium and hydroxyapatite coatings on Ti6Al4V alloy: in vitro biocompatibility and corrosion resistance : part II coatings enhance cell proliferation, corrosion resistance and implant integration T2 - Johnson Matthey Technology Review N2 - Part II presents the results which show that HA coatings significantly enhance MSC proliferation by 13% compared to the titanium alloy base, while titanium coatings also exhibit an 11% increase. Porosity inversely affects CP-Ti’s elasticity. Coatings with lower porosity demonstrate better corrosion resistance. HA coatings promote osteogenic activity and angiogenesis, which is crucial for implant integration. KW - Endoprosthesis implants KW - Biocompatible coatings KW - Porosity KW - Surface roughness KW - In vitro test KW - Elastic modulus Y1 - 2025 U6 - https://doi.org/10.1595/205651325X17290035905758 SN - 2056-5135 VL - 69 (2025) IS - 1 SP - 59 EP - 75 ER - TY - GEN A1 - Synodinos, Alexis D. A1 - Karnatak, Rajat A1 - Aguilar‐Trigueros, Carlos A. A1 - Gras, Pierre A1 - Heger, Tina A1 - Ionescu, Danny A1 - Maaß, Stefanie A1 - Musseau, Camille L. A1 - Onandia, Gabriela A1 - Planillo, Aimara A1 - Weiss, Lina A1 - Wollrab, Sabine A1 - Ryo, Masahiro T1 - The rate of environmental change as an important driver across scales in ecology T2 - Oikos N2 - Global change has been predominantly studied from the prism of ‘how much' rather than ‘how fast' change occurs. Associated to this, there has been a focus on environmental drivers crossing a critical value and causing so‐called regime shifts. This presupposes that the rate at which environmental conditions change is slow enough to allow the ecological entity to remain close to a stable attractor (e.g. an equilibrium). However, environmental change is occurring at unprecedented rates. Equivalently to the classical regime shifts, theory shows that a critical threshold in rates of change can exist, which can cause rate‐induced tipping (R‐tipping). However, the potential implications of R‐tipping in ecology remain understudied. We aim to facilitate the application of R‐tipping theory in ecology with the objective of identifying which properties (e.g. level of organisation) increase susceptibility to rates of change. First, we clarify the fundamental difference between tipping caused by the magnitude as opposed to the rate of change crossing a threshold. Then we present examples of R‐tipping from the ecological literature and seek the ecological properties related to higher sensitivity to rates of change. Specifically, we consider the role of the level of ecological organisation, spatial processes, eco‐evolutionary dynamics and pair–wise interactions in mediating or buffering rate‐induced transitions. Finally, we discuss how targeted experiments can investigate the mechanisms associated to increasing rates of change. Ultimately, we seek to highlight the need to better understand how rates of environmental change may induce ecological responses and to facilitate the systematic study of rates of environmental change in the context of current global change. KW - climate change KW - ecological communities KW - eco-evo feedbacks KW - transitions KW - global change KW - R-tipping KW - temporal ecology Y1 - 2023 U6 - https://doi.org/10.1111/oik.09616 SN - 0030-1299 VL - 2023 IS - 4 PB - Wiley ER - TY - GEN A1 - Yang, Yitong A1 - Weiß, Sabine T1 - In-situ investigation on cyclic bending deformation of oligocrystalline 316LVM steel for coronary stent application with EBSD T2 - International Conference on Strength of Materials 2022 N2 - The objective of this work is to investigate the strain localization and slip activation of the microstructure of oligo-crystalline 316LVM steel struts evolving during different cyclic bending deformation stages (number of cycles) and loading conditions (maximum stress and neutral). A micro-scale three-point bending fixture was designed and incorporated into a micro tensile/compression machine inside a scanning electron microscope (SEM) to perform in-situ electron backscatter diffraction (EBSD) measurements during different phases of cyclic fatigue testing. The following results were obtained: 1) The quantitative strain could be compared after each stage of deformation. 2) The rotation of the grains orientations is observed during the cyclic deformation while the morphology did not change significantly. The results contribute to the understanding of the evolution of the microstructure at low strain variations under bending fatigue conditions, and can support the prediction of the fatigue life of 316LVM stainless steel oligocrystalline microdevices like coronary artery stents. KW - Oligo-crystalline microstructure, in-situ bending fatigue test, EBSD, 316LVM austenitic steel, coronary stent, Y1 - 2022 UR - https://hal.science/hal-03829658v1 PB - HAL open science ER - TY - GEN A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Bouras, Dikra A1 - Obrosov, Aleksei A1 - Samad, Mohammed Abdul A1 - Montagne, Alex A1 - Abd-Elmonem, Assmaa A1 - Din, Sayed M El A1 - Weiß, Sabine T1 - Structural, mechanical and tribological performance of a nano structured biomaterial Co–Cr–Mo alloy synthesized via mechanical alloying T2 - Journal of Materials Research and Technology N2 - The influence of milling time on the tribological behavior of a Co–Cr–Mo alloy designed for biomedical applications, synthesized via mechanical alloying is investigated. Elemental Co, Cr and Mo powders are milled using different milling times (2, 6, 12 and 18 h) in a high-energy ball mill. The resulting powders were subjected to cold uniaxial and hot isostatic pressing respectively, followed by sintering to obtain cylindrical samples, which were evaluated for their structural, mechanical and the wear behavior. Results showed that the grain and crystallite sizes of the powders decreased with increasing milling time, reaching low values of <10 μm and 32 μm respectively, at higher milling times. Furthermore, the wear rates and the coefficients of friction were lower, at higher milling times due to high densities (96%), and higher elasto-plastic resistance, as presented by the H/E and H3/E2 values of 0.026 and 0.0021 GPa, respectively. Increased milling time enables the refinement of grains and reduction in porosity in the Co–Cr–Mo alloy, which in turn increases the alloy's elasto-plastic resistance and enhances its wear resistance. KW - Tribology KW - Wear resistance KW - Friction KW - Powder metallurgy KW - Co–Cr–Mo alloy Y1 - 2023 UR - https://www.sciencedirect.com/science/article/pii/S2238785423012796 U6 - https://doi.org/10.1016/j.jmrt.2023.06.031 SN - 2214-0697 VL - 25 SP - 2152 EP - 2165 ER - TY - GEN A1 - Çelik, Gülşah Aktaş A1 - Atapek, Şaban Hakan A1 - Polat, Şeyda A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Nitriding Effect on the Tribological Performance of CrN-, AlTiN-, and CrN/AlTiN-Coated DIN 1.2367 Hot Work Tool Steel T2 - Materials N2 - In this study, heat-treated and multisurface engineered DIN 1.2367 tool steel was subjected to room and elevated temperature wear tests, and the effect of nitriding on its tribological behavior was investigated. CrN, AlTiN, and CrN/AlTiN coatings with a total thickness of 2 µm were obtained by arc cathodic physical vapor deposition on conventional heat-treated and gas-nitrided steels. The white layer formed during nitriding was removed, and a diffusion layer (100 µm) was achieved in the cross section of the steel having a tempered martensitic matrix. The highest surface hardness was attained with an integral coating (CrN/AlTiN), and surface hardness increased even more after nitriding due to the formation of a multicomponent ceramic layer on top of the diffusion layer. The room temperature wear tests performed against an alumina counterpart revealed that (i) CrN/AlTiN-coated steel had the highest friction coefficient of 0.26, which further increased to 0.33 by nitriding due to the increase in shear strength, and that (ii) with increasing surface hardness, the specific wear rates (W) of the heat-treated and coated steels could be ranked as follows: WCrN/AlTiN < WAlTiN < WCrN. The wear rates decreased when nitriding was carried out prior to coating. In order to simulate the aluminum extrusion conditions, hot wear behavior of the surfaces against AA6080 alloy at 450 °C was investigated. The hot wear tests revealed that (i) high friction coefficients were reached due to the adhesive characteristic of aluminum to the surfaces, (ii) the nitrided and CrN/AlTiN-coated sample exhibited the lowest wear rate among all studied surfaces, and (iii) the film damage on the worn surfaces mostly occurred in the form of droplet delamination. KW - DIN 1.2367 KW - PVD coating KW - Wear KW - characterization Y1 - 2023 UR - https://www.mdpi.com/1996-1944/16/7/2804 U6 - https://doi.org/10.3390/ma16072804 SN - 1996-1944 VL - 16 IS - 7 ER - TY - GEN A1 - Safari, Athar A1 - Imran, Muhammad A1 - Weiss, Sabine T1 - A Comparative Study on Modified Johnson–Cook and Arrhenius-Type Constitutive Models to Predict the Hot Deformation Behaviour of Molybdenum-Hafnium-Carbide Alloy T2 - Journal of Materials Engineering and Performance N2 - Molybdenum alloys are commonly used as tool material for high-temperature deformation processes like forming or forging. For these types of application, the material has to withstand static load at elevated temperatures. To investigate the high-temperature performance of the material, uniaxial hot tensile tests were performed on a Mo-1.2% Hf-0.1% C alloy (MHC) over the temperature range of 1173-1473 K with intervals of 100 K and strain rates of 0.001, 0.01 and 0.1 s−1 up to the fracture of the specimen. The flow stress decreases with increase in temperature and the reduction in strain rate. This behaviour could be related to the increasing rate of restoration mechanisms, i.e. dynamic recrystallization or recovery as well as to the decrease in the strain hardening rate. Microstructure of the two most critical hot deformation conditions were shown and compared. Based on modified Johnson–Cook and strain-compensated Arrhenius-type models, constitutive equations were established to predict the high-temperature flow stress of the respective MHC alloy. The accuracy of both models was evaluated by comparing the predicted stress values and the values obtained from experiments. Correlation coefficient, average absolute relative error, the number of material constants involved and the computational time required for evaluating the constants were calculated to quantify and compare the precision of both models. The flow stress values predicted by the constitutive equations are in good agreement with the experimental results. At lower strain rates (0.001 and 0.01 s−1), distinct deviation from the experimental results can be observed for the modified Johnson–Cook model. Despite the longer evaluation time and the larger number of material constants, the deformation behaviour, tracked by the Arrhenius-type model is more accurate throughout the entire deformation process. KW - constitutive equation KW - flow stress KW - hot tensile deformation KW - molybdenum-hafnium-carbide alloy (MHC) Y1 - 2021 U6 - https://doi.org/10.1007/s11665-021-05464-2 SN - 1059-9495 SN - 1544-1024 VL - 30 IS - 3 SP - 1945 EP - 1956 ER - TY - GEN A1 - Bouras, Dikra A1 - Fellah, Mamoun A1 - Barille, Regis A1 - Weiß, Sabine A1 - Samad, Mohammed Abdul A1 - Alburaikan, Alhanouf A1 - Khalifa, Hamiden Abd El-Wahed A1 - Obrosov, Aleksei T1 - Improvement of photocatalytic performance and sensitive ultraviolet photodetectors using AC-ZnO/ZC-Ag2O/AZ-CuO multilayers nanocomposite prepared by spin coating method T2 - Journal of Science: Advanced Materials and Devices N2 - Morphological and optical properties of a multilayer film (CAZO/CZAO/ZACO) prepared by spin-coating method and deposited on a glass substrate were evaluated. The study was initially carried out for each layer, individually and then as a multilayer subsequently. Structural properties using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), infrared spectra (IR) and X-ray photoelectron Spectroscopy (XPS) showed the presence of three phases of zinc, copper and silver oxides at different levels. The CZAO sample observed with scanning electron microscope (SEM) showed an excellent porous surface with a large deformation in the multilayer configuration. Doping with zinc and copper in the silver crystal lattice improved the crystal structure and reduced the optical energy gap, thus increasing the optical absorbance and refractive index. The dielectric constants and showed an increase in the optical polarization values for lower photonic energies. The maximum degradation rate for photocatalysts of methylene blue was 89 % for a 5-h exposure period with CAZO/CZAO/ZACO while it reached 71 % for the CZAO sample during the same time period. The sensitivity of samples to light proved that the presence of ultraviolet radiation increases the number of holes trapped by oxygen ions and causes more free electrons and contribute to a better production of photocurrent than in darkness. KW - Multilayer CAZO/CZAO/ZACO KW - Spin-coating KW - Energy gap KW - Photocatalysis KW - Photodetector KW - Nanostructures KW - Nanocomposites Y1 - 2024 U6 - https://doi.org/10.1016/j.jsamd.2023.100642 SN - 2468-2179 VL - 9 IS - 1 ER - TY - GEN A1 - Yang, Yitong A1 - Eisentraut, Mark A1 - Weiß, Sabine A1 - Bolz, Sebastian T1 - Comparison of the data from two EBSD system to verify the accuracy of the technique T2 - AK Treffen Mikrostrukturcharakterisierung im REM”, Ruhr-Uni Bochum, 30. November – 1. Dezember 2023 Y1 - 2023 UR - https://www.researchgate.net/publication/377636122_Comparison_of_the_data_from_two_EBSD_system_to_verify_the_accuracy_of_the_technique_AK-Treffen_Mikrostrukturcharakterisierung_im_REM_Ruhr-Uni_Bochum CY - Bochum ER - TY - GEN A1 - Emdadi, Aliakbar A1 - Yang, Yitong A1 - Bolz, Sebastian A1 - Stryzhyboroda, Oleg A1 - Tovar, Michael A1 - Gein, Sergej A1 - Hecht, Ulrike A1 - Weiß, Sabine T1 - Mechanisms of necklace recrystallization in a BCC Fe-Al-Ta alloy with strengthening Laves phase precipitates T2 - Scripta Materialia N2 - A necklace structure composed of fine grains formed by dynamic recrystallization was uncommonly observed at the pre-existing grain boundaries during the hot compression of a BCC Fe-25Al-1.5Ta alloy containing C14 - (Fe, Al)2Ta Laves phase precipitates. Two possible mechanisms for necklace formation were proposed; particle-stimulated nucleation and grain boundary bulging, depending on whether the original grain boundaries are occupied by C14 particles, or they are free of them. Recrystallization was initiated preferentially around the clusters of large particles at the boundaries containing particles. In contrast, the bulging of the original grain boundaries by strain-induced boundary migration was observed as a preliminary stage for necklace formation at the particle-free boundaries. The necklace structure expanded into the deformed volume in such a way that low-angle subgrain boundaries decorating the necklace layers transformed into grains with increasing deformation strain. Y1 - 2023 UR - https://www.sciencedirect.com/science/article/pii/S1359646223004281 U6 - https://doi.org/10.1016/j.scriptamat.2023.115705 SN - 1359-6462 SN - 1872-8456 VL - 237 ER - TY - GEN A1 - Lasko, Galina A1 - Yang, Yitong A1 - Weiss, Sabine A1 - Schmauder, Siegfried A1 - Dogahe, Kiarash T1 - FEM Simulations of Fatigue Crack Initiation in the Oligocrystalline Microstructure of Stents T2 - Materials N2 - For over two decades, vascular stents have been widely used to treat clogged vessels,serving as a scaffold to enlarge the narrowed lumen and recover the arterial flow area. High-purityoligocrystalline austenitic steel is usually applied for the production of stents. Despite the popularityand benefit of stenting, it still may cause serious clinical adverse issues, such as in-stent restenosisand stent fracture. Therefore, the study of the mechanical properties of stents and in particularthe prediction of their life cycles are in the focus of materials research. In our contribution, withinthe finite element method, a two-scale model of crack initiation in the microstructure of stents iselaborated. The approach is developed on the basis of the physically based Tanaka–Mura model(TMM), considering the evolution of shear bands during the crack initiation phase. The model allowsfor the analysis of the microstructure with respect to the life cycles of real materials. The effects ofdifferent loading conditions, grain orientation, and thickness of the specimen on Wöhler curves wereanalysed. It was found that the microstructural features of oligocrystals are very sensitive to differentloading conditions with respect to their fatigue behaviour and play a major role in fatigue crackinitiation. Different grain-orientation distributions result in qualitative and quantitative differencesin stress distribution and in the number of cycles for crack initiation. It was found that presence ofa neutral zone in the cut-out of the microstructure under three-point-bending loading conditionschanges the qualitative and quantitative patterns of stress distribution and affects the number ofcycles for crack initiation. It was found that under both tensile and bending loading conditions,thicker specimens require more cycles for crack initiation. The Wöhler curves for crack initiation inoligocrystalline microstructures of stents could be compared with the ones in the experiment, takinginto account that for high cyclic fatigue (HCF), typically, more than 70% of the cycles refer to crackinitiation. The developed numerical tools could be used for the material design of stents KW - SCHM 746/222-1 KW - WE 2671/11-1 Y1 - 2023 UR - https://www.mdpi.com/1996-1944/16/17/6003 U6 - https://doi.org/10.3390/ma16176003 VL - 16 IS - 17 ER - TY - GEN A1 - Dahmani, Marwa A1 - Fellah, Mamoun A1 - Hezil, Naouel A1 - Benoudia, Mohamed-Cherif A1 - Obrosov, Aleksei A1 - El-Hiti, Gamal A. A1 - Weiß, Sabine T1 - Bioactivity and tribological performance of a novel nano-biomaterial beta-type Ti-alloy T2 - Journal of materials research and technology N2 - This study investigates the bioactivity; wear performance, and topography of a novel beta-type titanium-based alloy using techniques such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and 2D and 3D analysis. The tribological test was evaluated using a ball-on-disk tribometer in a wet environment. Different loads of 2, 6, and 10 N were applied during the evolution. The data results indicate a significant effect of the milling process on the formation of the hydroxyapatite layer on the surfaces of the Ti–Nb–Mo alloy. Both the wear volume and rate showed a consistent trend of decrease as the milling time increased from 2 to 12 h for all applied loads. The minimum values of wear and volume were reached after 12 h of milling. The improvement in tribological behavior can be attributed to the improved mechanical properties of the alloys. In addition, the significant presence of niobium (Nb) and molybdenum (Mo) plays a critical role in achieving high coefficient of friction values. The primary wear mechanism observed in the Ti–25Nb–25Mo system was adhesive wear in addition to abrasive wear. With its lower Young's modulus and favorable biological and tribological properties, the Ti–25Nb–25Mo alloy represents a promising option for bone tissue applications in orthopedics. KW - Ti–25Nb–25Mo KW - Milling time KW - Bioactivity KW - Hydroxyapatite KW - Friction coefficient KW - Wear rate KW - Biomaterials Y1 - 2025 UR - https://www.sciencedirect.com/science/article/pii/S2238785425006908 U6 - https://doi.org/https://doi.org/10.1016/j.jmrt.2025.03.180 SN - 2214-0697 VL - 36 SP - 2297 EP - 2316 PB - Elsevier CY - Amsterdam ER -