@misc{FellahHezilTouhamietal., author = {Fellah, Mamoun and Hezil, Naouel and Touhami, Mohamed Zine and Obrosov, Aleksei and Weiß, Sabine and Kashkarov, Egor B. and Lider, Andrey M. and Montagne, Alex and Iost, Alain}, title = {Enhanced Structural and Tribological Performance of Nanostructured Ti-15Nb Alloy for Biomedical Applications}, series = {Results in Physics}, volume = {15}, journal = {Results in Physics}, issn = {2211-3797}, doi = {10.1016/j.rinp.2019.102767}, pages = {7}, abstract = {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.}, language = {en} } @misc{StendalBambachEisentrautetal., author = {Stendal, Johan Andreas and Bambach, Markus and Eisentraut, Mark and Sizova, Irina and Weiß, Sabine}, title = {Applying Machine Learning to the Phenomenological Flow Stress Modeling of TNM-B1}, series = {Metals}, volume = {9}, journal = {Metals}, number = {2}, issn = {2075-4701}, doi = {10.3390/met9020220}, pages = {18}, abstract = {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.}, language = {en} } @misc{EisentrautBolzSizovaetal., author = {Eisentraut, Mark and Bolz, Sebastian and Sizova, Irina and Bambach, Markus and Weiß, Sabine}, title = {Development of a heat treatment strategy for the γ-TiAl based alloy TNM-B1 to increase the hot workability}, series = {SN Applied Sciences}, volume = {1}, journal = {SN Applied Sciences}, number = {11}, issn = {2523-3963}, doi = {10.1007/s42452-019-1563-4}, pages = {8}, language = {en} } @misc{StendalEisentrautSizovaetal., author = {Stendal, Johan Andreas and Eisentraut, Mark and Sizova, Irina and Bolz, Sebastian and Bambach, Markus and Weiß, Sabine}, title = {Effect of heat treatment on the workability of hot isostatically pressed TNM-B1}, series = {AIP Conference Proceedings}, volume = {2113}, journal = {AIP Conference Proceedings}, number = {1}, isbn = {978-0-7354-1847-9}, doi = {10.1063/1.5112544}, language = {en} } @incollection{FellahHezilAbderrahimetal., author = {Fellah, Mamoun and Hezil, Naouel and Abderrahim, Karima and Samad, Mohammed Abdul and Montagne, Alex and Mejias, Alberto and Iost, Alain and Kossman, Stephania and Chekalkin, Timofey and Obrosov, Aleksei and Weiß, Sabine}, title = {Investigating the Effect of Sintering Temperature on Structural and Tribological Properties of a Nanostructured Ti-20Nb-13Zr Alloy for Biomedical Applications}, series = {Characterization of Minerals, Metals, and Materials}, booktitle = {Characterization of Minerals, Metals, and Materials}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-36628-5}, issn = {2367-1181}, doi = {10.1007/978-3-030-36628-5_61}, pages = {619 -- 629}, abstract = {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.}, language = {en} } @misc{FellahHezilTouhamietal., author = {Fellah, Mamoun and Hezil, Naouel and Touhami, Mohamed Zine and Hussien, Mohammed A. and Montagne, Alex and Mejias, Alberto and Iost, Alain and Kossman, Stephania and Chekalkin, Timofey and Obrosov, Aleksei and Weiß, Sabine}, title = {Effect of Sintering Temperature on Mechanical and Tribological Behavior of Ti-Ni Alloy for Biomedical Applications}, series = {TMS 2020 149th Annual Meeting \& Exhibition Supplemental Proceedings}, journal = {TMS 2020 149th Annual Meeting \& Exhibition Supplemental Proceedings}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-36295-9}, issn = {2367-1181}, doi = {10.1007/978-3-030-36296-6_157}, pages = {1701 -- 1710}, abstract = {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.}, language = {en} } @misc{HezilFellahMontagneetal., author = {Hezil, Naouel and Fellah, Mamoun and Montagne, Alex and Iost, Alain and Obrosov, Aleksei and Weiß, Sabine}, title = {Removal of Chromium (VI) from Water onto Activated Carbon by Adsorption in Dynamic Mode}, series = {TMS 2020 149th Annual Meeting \& Exhibition Supplemental Proceedings}, journal = {TMS 2020 149th Annual Meeting \& Exhibition Supplemental Proceedings}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-36295-9}, issn = {2367-1181}, doi = {https://doi.org/10.1007/978-3-030-36296-6_80}, pages = {855 -- 863}, abstract = {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.}, language = {en} } @misc{EvdokimovDoynovOssenbrinketal., author = {Evdokimov, Anton and Doynov, Nikolay and Ossenbrink, Ralf and Obrosov, Aleksei and Weiß, Sabine and Michailov, Vesselin}, title = {Thermomechanical laser welding simulation of dissimilar steel-aluminum overlap joints}, series = {International Journal of Mechanical Sciences}, volume = {190}, journal = {International Journal of Mechanical Sciences}, issn = {1879-2162}, doi = {10.1016/j.ijmecsci.2020.106019}, pages = {18}, abstract = {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.}, language = {en} } @misc{BaigonakovaMarchenkoChekalkinetal., author = {Baigonakova, Gulsharat and Marchenko, Ekaterina and Chekalkin, Timofey and Kang, Ji-hoon and Weiß, Sabine and Obrosov, Aleksei}, title = {Influence of Silver Addition on Structure, Martensite Transformations and Mechanical Properties of TiNi-Ag Alloy Wires for Biomedical Application}, series = {Materials}, volume = {13}, journal = {Materials}, number = {21}, issn = {1996-1944}, doi = {10.3390/ma13214721}, pages = {11}, abstract = {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.}, language = {en} } @misc{HazilFellahMontagneetal., author = {Hazil, Naouel and Fellah, Mamoun and Montagne, Alex and Iost, Alain and Obrosov, Aleksei and Weiß, Sabine}, title = {Study of the photocatalytic degradation of Orange methyl dye in the presence of titanium dioxide}, series = {La Troisi{\`e}me Conf{\´e}rence M{\´e}diterran{\´e}enne de la Biodiversit{\´e} 2019 (BIODIV 2019)}, journal = {La Troisi{\`e}me Conf{\´e}rence M{\´e}diterran{\´e}enne de la Biodiversit{\´e} 2019 (BIODIV 2019)}, publisher = {L'ASCOB-SYRTIS}, address = {Hammamet, Tunisie}, pages = {105}, abstract = {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\%.}, language = {en} } @misc{PrechavutWeiss, author = {Prechavut, Ananya and Weiß, Sabine}, title = {Analyse der Korrosionsprodukte eines im CO2 Methanisierungsprozess verwendeten Edelstahlflansches aus 316L}, abstract = {Die Weltklimakonferenz fordert eine massive Senkung der Treibhausgasemissionen mittels Abkehr von der Nutzung fossiler Brennstoffe hin zur Verwendung umweltvertr{\"a}glich hergestellter Energie. Da erneuerbare Energien aber bisher nicht durchweg bedarfsgerecht zur Verf{\"u}gung stehen und schlecht speicherbar sind, besteht eine kurzfristige L{\"o}sungsm{\"o}glichkeit in Umwandlung, Speicherung und Wiederverwendung klimasch{\"a}dlicher Verbrennungsgase. Eine effiziente L{\"o}sung 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. Reaktionsbeh{\"a}lter und Leitungen bestehen {\"u}blicherweise aus Edelstahl. Durch hohe Umgebungs-temperatur und aggressive Umgebungsmedien kann auch bei dem normalerweise temperatur- und korrosionsbest{\"a}ndigen Werkstoff 316L Korrosion auftreten, Materialeigenschaften beeinflussen und zu Materialversagen f{\"u}hren. 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 Korrosionsbel{\"a}ge gefunden. Abh{\"a}ngig von ihrer Lage im Bauteil sind diese Korrosionsschichten sehr unterschiedlich aufgebaut. Mikrostruktur und Elementzusammensetzung der Schichten wurden mittels Rasterelektronenmikroskopie kombiniert mit energiedispersiver R{\"o}ntgenspektroskopie analysiert. W{\"a}hrend 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 br{\"u}chiger Passivfilm) identifiziert. Die Mehrschichtzone setzt sich aus kolumnaren und granularen Strukturen zusammen, die Partikelansammlungen bestehen aus zylinderf{\"o}rmigen und kugelf{\"o}rmigen Partikeln. Die Elementzusammensetzung innerhalb der Korrosionsschichten l{\"a}sst auf Kontaktkorrosion verursacht durch das Material der Dichtringe schließen.}, language = {de} } @misc{PrechavutWeiss, author = {Prechavut, Ananya and Weiß, Sabine}, title = {Corrosion Analysis of a 316L Stainless Steel Gas Outlet Sealed with a Copper Ring Used in the CO2 Methanation Process}, pages = {1}, abstract = {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.}, language = {en} } @misc{EisentrautStendalBolzetal., author = {Eisentraut, Mark and Stendal, Johan Andreas and Bolz, Sebastian and Bambach, Markus and Weiß, Sabine}, title = {Applying a softening adapted acceleration to the hot deformation of TNM-B1}, series = {MRS Fall Meeting 2020}, journal = {MRS Fall Meeting 2020}, abstract = {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.}, language = {en} } @misc{MorozovaObrosovNaumovetal., author = {Morozova, Iuliia and Obrosov, Aleksei and Naumov, Anton and Kr{\´o}licka, Aleksandra and Golubev, Iurii and Bokov, Dmitry O. and Doynov, Nikolay and Weiß, Sabine and Michailov, Vesselin}, title = {Impact of Impulses on Microstructural Evolution and Mechanical Performance of Al-Mg-Si Alloy Joined by Impulse Friction Stir Welding}, series = {Materials}, volume = {14}, journal = {Materials}, number = {2}, issn = {1996-1944}, doi = {https://doi.org/10.3390/ma14020347}, abstract = {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.}, language = {en} } @misc{BiedunkiewiczFigielGarbiecetal., author = {Biedunkiewicz, Anna and Figiel, Paweł and Garbiec, Dariusz and Obrosov, Aleksei and Pawlyta, Mirosława and Biedunkiewicz, Witold and Pruss, Przemysław and Rokosz, Krzysztof and Wr{\´o}bel, Rafał and Raaen, Steinar and Weiß, Sabine and Bokov, Dmitry O.}, title = {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}, series = {Materials}, volume = {14}, journal = {Materials}, number = {1}, issn = {1996-1944}, doi = {https://doi.org/10.3390/ma14010231}, abstract = {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.}, language = {en} } @misc{StendalEisentrautSizovaetal., author = {Stendal, Johan Andreas and Eisentraut, Mark and Sizova, Irina and Bolz, Sebastian and Weiß, Sabine and Bambach, Markus}, title = {Accelerated hot deformation and heat treatment of the TiAl alloy TNM-B1 for enhanced hot workability and controlled damage}, series = {Journal of Materials Processing Technology}, volume = {Vol. 291}, journal = {Journal of Materials Processing Technology}, issn = {0924-0136}, doi = {10.1016/j.jmatprotec.2020.116999}, pages = {12}, language = {en} } @misc{FouziaFellahHeziletal., author = {Fouzia, Hammadi and Fellah, Mamoun and Hezil, Naouel and Aissani, Linda and Mimanne, Goussem and Mechachti, Said and Samad, Mohammed Abdul and Montagne, Alex and Iost, Alain and Weiß, Sabine and Obrosov, Aleksei}, title = {The effect of milling time on the microstructure and mechanical properties of Ti-6Al-4Fe alloys}, series = {Materials Today Communications}, volume = {27}, journal = {Materials Today Communications}, issn = {2352-4928}, doi = {10.1016/j.mtcomm.2021.102428}, pages = {11}, abstract = {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.}, language = {en} } @misc{GrudininSidelevBleykheretal., author = {Grudinin, V. A. and Sidelev, D. V. and Bleykher, G. A. and Yuriev, Yu N. and Krivobokov, V. P. and Berlin, E. V. and Grigoriev, V. Yu and Obrosov, Aleksei and Weiß, Sabine}, title = {Hot target magnetron sputtering enhanced by RF-ICP source for CrNx coatings deposition}, series = {Vacuum}, volume = {191}, journal = {Vacuum}, issn = {0042-207X}, doi = {10.1016/j.vacuum.2021.110400}, pages = {9}, abstract = {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.}, language = {en} } @misc{KrzywińskiSadowskiStefaniuketal., author = {Krzywiński, Kamil and Sadowski, Łukasz and Stefaniuk, Damian and Obrosov, Aleksei and Weiß, Sabine}, title = {Engineering and Manufacturing Technology of Green Epoxy Resin Coatings Modified with Recycled Fine Aggregates}, series = {International Journal of Precision Engineering and Manufacturing-Green Technology}, volume = {9}, journal = {International Journal of Precision Engineering and Manufacturing-Green Technology}, number = {1}, issn = {2198-0810}, doi = {10.1007/s40684-021-00377-w}, pages = {253 -- 271}, abstract = {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.}, language = {en} } @misc{AissaniFellahChadlietal., author = {Aissani, Linda and Fellah, Mamoun and Chadli, Abdel Hakim and Samad, Mohammed Abdul and Cheriet, Abderrahmane and Salhi, Faiza and Nouveau, Corinne and Weiß, Sabine and Obrosov, Aleksei and Alhussein, Akram}, title = {Investigating the effect of nitrogen on the structural and tribo-mechanical behavior of vanadium nitride thin films deposited using R.F. magnetron sputtering}, series = {Journal of Materials Science}, volume = {56}, journal = {Journal of Materials Science}, number = {30}, issn = {1573-4803}, doi = {10.1007/s10853-021-06393-0}, pages = {17319 -- 17336}, abstract = {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.}, language = {en} }