@misc{MeissnerWeissBraueretal., author = {Meissner, Andreas and Weiß, Sabine and Brauer, H. and Fischer, Annette}, title = {Peculiarities in stent fatigue testing}, series = {Fatigue 2006, Proceedings 9th International Fatigue Congress May 14-19, 2006}, journal = {Fatigue 2006, Proceedings 9th International Fatigue Congress May 14-19, 2006}, publisher = {Georgia Institute of Technology}, address = {Atlanta, Ga.}, language = {en} } @misc{WeissMeissnerGuillardeauetal., author = {Weiß, Sabine and Meissner, Andreas and Guillardeau, A. and Dudzinski, Wlodzimierz and Fischer, Annette}, title = {Characterisation of microstructure and microtexture of coronary artery stents after fatigue deformation}, series = {Fatigue 2006, Proceedings 9th International Fatigue Congress May 14-19, 2006 Atlanta}, journal = {Fatigue 2006, Proceedings 9th International Fatigue Congress May 14-19, 2006 Atlanta}, publisher = {Georgia Institute of Technology}, address = {Atlanta, Ga.}, language = {en} } @inproceedings{WeissGleisingSchremmeretal., author = {Weiß, Sabine and Gleising, B. and Schremmer, S. and Dudzinski, Wlodzimierz}, title = {Charakterisierung der Mikrostruktur von Kobalt-Chrom-Molybd{\"a}n Dr{\"a}hten}, series = {Fortschritte in der Metallographie, Vortragstexte der 39. Metallographie-Tagung, 14. - 16. September 2005 in Erlangen}, booktitle = {Fortschritte in der Metallographie, Vortragstexte der 39. Metallographie-Tagung, 14. - 16. September 2005 in Erlangen}, publisher = {Werkstoff-Informationsgesellschaft}, address = {Frankfurt}, pages = {207 -- 212}, language = {de} } @misc{AmerELGhazalyShashetal., author = {Amer, A. E. and EL-Ghazaly, S. A. and Shash, Y. S. and Weiß, Sabine}, title = {Influence of microstructural changes and grain boundary precipitation on the behaviour of 25Ni-15Cr-2Ti superalloy during high temperature creep}, series = {Materials Science Forum}, journal = {Materials Science Forum}, number = {Vol. 475-479}, issn = {1662-9752}, pages = {643 -- 649}, language = {en} } @inproceedings{WeissDudzinskiTikhovskiy, author = {Weiß, Sabine and Dudzinski, Wlodzimierz and Tikhovskiy, I.}, title = {TEM Observation of Deformation Structures in High Nitrogen Steel}, series = {Proceedings of the 7th International Conference on High Nitrogen Steels, Ostend, Belgium, September 19 - 22, 2004}, booktitle = {Proceedings of the 7th International Conference on High Nitrogen Steels, Ostend, Belgium, September 19 - 22, 2004}, publisher = {GRIPS-Media GmbH}, address = {Bad Harzburg}, isbn = {3-937057-09-9}, pages = {225 -- 228}, language = {en} } @misc{TikhovskiyFischerWeiss, author = {Tikhovskiy, I. and Fischer, Annette and Weiß, Sabine}, title = {Cyclic deformation behaviour of austenitic CrMnMoN steel in solution annealed and cold worked states}, series = {High nitrogen steels : international conference}, journal = {High nitrogen steels : international conference}, number = {2}, pages = {259 -- 263}, language = {en} } @inproceedings{PyzallaStempniewiczSanderetal., author = {Pyzalla, A. and Stempniewicz, M. and Sander, M. and Weiß, Sabine and Hinkel, P.}, title = {Anwendung pr{\"a}parativer Methoden aus der Werkstoffkunde zur Untersuchung von Sauropodenknochen}, series = {Fortschritte in der Metallographie, Vortragstexte der 38. Metallographie-Tagung, 29. September - 1. Oktober 2004 in Bochum}, booktitle = {Fortschritte in der Metallographie, Vortragstexte der 38. Metallographie-Tagung, 29. September - 1. Oktober 2004 in Bochum}, publisher = {Werkstoff-Informationsgesellschaft}, address = {Frankfurt}, pages = {217 -- 221}, language = {de} } @inproceedings{WeissGleisingDudzinski, author = {Weiß, Sabine and Gleising, B. and Dudzinski, Wlodzimierz}, title = {Mikrostruktur- und Mikrotextur-Charakterisierung nach der Verformung des hochstickstoffhaltigen Edelstahls (1.4452)}, series = {Fortschritte in der Metallographie, Vortragstexte der 38. Metallographie-Tagung, 29. September - 1. Oktober 2004 in Bochum}, booktitle = {Fortschritte in der Metallographie, Vortragstexte der 38. Metallographie-Tagung, 29. September - 1. Oktober 2004 in Bochum}, publisher = {Werkstoff-Informationsgesellschaft}, address = {Frankfurt}, isbn = {3-88355-336-0}, pages = {103 -- 108}, language = {de} } @inproceedings{WeissKlement, author = {Weiß, Sabine and Klement, U.}, title = {Orientation determination on non planar surfaces}, series = {Proceedings of the CHANNEL Users Meeting 2004 in Ribe, Denmark}, booktitle = {Proceedings of the CHANNEL Users Meeting 2004 in Ribe, Denmark}, publisher = {Chalmers University of Technology}, address = {G{\"o}teborg}, pages = {62 -- 66}, language = {en} } @misc{TikhovskiyGleisingWeissetal., author = {Tikhovskiy, I. and Gleising, B. and Weiß, Sabine and Fischer, Annette}, title = {Mikrostrukturentwicklung des hochstickstofflegierten austenitischen Stahles X13CrMnMoN 18-14-3 unter zyklischer Beanspruchung}, series = {Fortschritte in der Metallographie, Berichte der 11. Internationalen Metallographie-Tagung Leoben, 11. bis 13. September 2002}, journal = {Fortschritte in der Metallographie, Berichte der 11. Internationalen Metallographie-Tagung Leoben, 11. bis 13. September 2002}, publisher = {Werkstoff-Informationsgesellschaft}, address = {Frankfurt}, isbn = {3-88355-313-1}, pages = {43 -- 50}, language = {de} } @misc{TikhovskiyWeissFischer, author = {Tikhovskiy, I. and Weiß, Sabine and Fischer, Annette}, title = {Fatigue Damage Evolution of Cold-Worked Austenitic Nickel-Free High-Nitrogen X13CrMnMoN18 14 3 (1.4452) Steel}, series = {Proceeding of the Fifth International Conference on Low Cycle Fatigue}, journal = {Proceeding of the Fifth International Conference on Low Cycle Fatigue}, publisher = {DVM, Deutscher Verband f{\"u}r Materialforschung und -pr{\"u}fung e.V.}, address = {Berlin}, language = {en} } @misc{WeissMattissenDudzinskietal., author = {Weiß, Sabine and Mattissen, D. and Dudzinski, Wlodzimierz and Fischer, Annette}, title = {Microstructure of the Laser Beam Welded Iron-Based Superalloy A286 after High Temperature Creep}, series = {Conference Proceedings of the Materials Week, Munich 2002}, journal = {Conference Proceedings of the Materials Week, Munich 2002}, publisher = {Werkstoff-Informationsgesellschaft}, address = {Frankfurt}, isbn = {3-88355-314-X}, pages = {S. 142}, language = {en} } @misc{WeissMeissnerFischer, author = {Weiß, Sabine and Meißner, Andreas and Fischer, Alfons}, title = {Microstructural changes within similar coronary stents produced from two different austenitic steels}, series = {Journal of the Mechanical Behavior of Biomedical Materials}, volume = {2}, journal = {Journal of the Mechanical Behavior of Biomedical Materials}, number = {2}, issn = {1751-6161}, pages = {210 -- 216}, language = {en} } @phdthesis{Weiss, author = {Weiß, Sabine}, title = {Einfluss der Wenigkristallinit{\"a}t auf das Verformungsverhalten von Werkstoffen und Bauteilen der Medizintechnik}, publisher = {VDI}, address = {D{\"u}sseldorf}, isbn = {978-3-18-373405-4}, pages = {VI, 172}, language = {de} } @misc{WeissFischer, author = {Weiß, Sabine and Fischer, Annette}, title = {Bruchverhalten hochstickstoffhaltiger St{\"a}hle bei Erm{\"u}dungs¬bean-spruchung}, series = {Tagungsband Gef{\"u}ge und Bruch, 26. - 27. Februar 2007 Bochum}, journal = {Tagungsband Gef{\"u}ge und Bruch, 26. - 27. Februar 2007 Bochum}, address = {Bochum}, language = {de} } @misc{FischerBurgaudAmeretal., author = {Fischer, Annette and Burgaud, D. and Amer, A. E. and Weiß, Sabine}, title = {The fatigue Aspect in metal on metal wear}, series = {Cost 533 biotribology, materials for improved wear resistance of total artificial joints, 29 october 2007, Fundaci{\´o}n Tekniker, Eibar, Spain}, journal = {Cost 533 biotribology, materials for improved wear resistance of total artificial joints, 29 october 2007, Fundaci{\´o}n Tekniker, Eibar, Spain}, publisher = {Tekniker}, address = {Eibar, Guip{\´u}zcoa}, isbn = {978-84-932064-4-4}, pages = {35 -- 44}, language = {en} } @misc{WeissMeissnerFischer, author = {Weiß, Sabine and Meissner, Andreas and Fischer, Annette}, title = {Zyklische Beanspruchung und Mikrostruktur von koronaren Stents}, series = {Fortschritte der Kennwertermittlung f{\"u}r Forschung und Praxis, Tagung Werkstoffpr{\"u}fung 2006, 07. und 08. Dezember 2006, Bad Neuenahr}, journal = {Fortschritte der Kennwertermittlung f{\"u}r Forschung und Praxis, Tagung Werkstoffpr{\"u}fung 2006, 07. und 08. Dezember 2006, Bad Neuenahr}, editor = {Borsutzki, Michael}, publisher = {Stahleisen}, address = {D{\"u}sseldorf}, isbn = {3-514-00734-9}, pages = {S. 463}, language = {de} } @misc{FischerMeissnerBraueretal., author = {Fischer, Annette and Meissner, Andreas and Brauer, H. and Weiß, Sabine}, title = {Stent fatigue testing according to in vivo strain cycles}, series = {Journal of Biomechanics}, volume = {39}, journal = {Journal of Biomechanics}, number = {Suppl. 1}, issn = {1873-2380}, pages = {S. 591}, language = {en} } @misc{FischerTikhovskiyBuescheretal., author = {Fischer, Annette and Tikhovskiy, I. and B{\"u}scher, R. and Weiß, Sabine}, title = {Mechanische und tribologische Eigenschaften hochstickstoffhaltigen Austeniten}, series = {Materialwissenschaft und Werkstofftechnik}, volume = {39}, journal = {Materialwissenschaft und Werkstofftechnik}, number = {9}, isbn = {1521-4052}, pages = {747 -- 754}, language = {de} } @misc{WeissMeissner, author = {Weiß, Sabine and Meissner, Andreas}, title = {Erm{\"u}dung und Mikrostruktur von koronaren Stents}, series = {Materialwissenschaft und Werkstofftechnik}, volume = {37}, journal = {Materialwissenschaft und Werkstofftechnik}, number = {9}, issn = {1521-4052}, pages = {755 -- 761}, language = {de} } @misc{FischerWeissWimmer, author = {Fischer, Alfons and Weiß, Sabine and Wimmer, Markus A.}, title = {The Tribological Difference between Biomedical Steels and CoCrMo-Alloys}, series = {Journal of the Mechanical Behavior of Biomedical Materials}, volume = {9}, journal = {Journal of the Mechanical Behavior of Biomedical Materials}, issn = {1878-0180}, pages = {50 -- 62}, language = {en} } @misc{RanjbarnodehWeissHankeetal., author = {Ranjbarnodeh, Eslam and Weiß, Sabine and Hanke, Stefanie and Fischer, Annette}, title = {EBSD characterization of the effect of welding parameters on HAZ of AISI409}, series = {Journal of Mining and Metallurgy : B}, volume = {48}, journal = {Journal of Mining and Metallurgy : B}, number = {1}, issn = {1450-5339}, pages = {115 -- 121}, language = {en} } @misc{WeissSchnauberFischer, author = {Weiß, Sabine and Schnauber, T. and Fischer, Annette}, title = {Microstructure Characterization of thin structures after deformation}, series = {Materials and devices for smart systems III, symposium held December 1 - 4, 2008, Boston, Massachusetts}, journal = {Materials and devices for smart systems III, symposium held December 1 - 4, 2008, Boston, Massachusetts}, editor = {Su, Ji}, publisher = {MRS}, address = {Warrendale, Pa.}, isbn = {978-1-605-11101-8}, pages = {V11 -- 19}, language = {en} } @misc{AmerWeissFischer, author = {Amer, A. E. and Weiß, Sabine and Fischer, Annette}, title = {Improvement of fatigue resistance of low-nickel stainless steels for biomedical applications compared to CoCr-alloys}, series = {Steel grips}, volume = {7}, journal = {Steel grips}, number = {6}, issn = {1866-8453}, pages = {457 -- 461}, language = {en} } @misc{WeissSzymczakMeissner, author = {Weiß, Sabine and Szymczak, H. and Meissner, Andreas}, title = {Fatigue and endurance of coronary stents}, series = {Materialwissenschaft und Werkstofftechnik}, volume = {40}, journal = {Materialwissenschaft und Werkstofftechnik}, number = {1-2}, issn = {1521-4052}, pages = {61 -- 64}, language = {en} } @misc{GarkasWeissWang, author = {Garkas, Wagdi and Weiß, Sabine and Wang, Q. M.}, title = {(Cr1-x Al x)N as a candidate for corrosion protection in high temperature segments of CCS plants}, series = {Environmental Earth Sciences}, journal = {Environmental Earth Sciences}, issn = {1866-6280}, doi = {10.1007/s12665-013-2646-y}, abstract = {Three (Cr1-x Al x )N (x = 0.33, 0.5, 0.66) coatings were deposited on Ni-super alloy IN718 using reactive magnetron sputtering. The oxidation behavior of all coatings at 900 °C up to 500 h in air was studied. Furthermore, the corrosion behavior of the (Cr0.33,Al0.66)N coating at 900 °C (corrosion type I) by spraying a uniform salt scale of Na2SO4 on the sample surface (1 mg/cm2) was investigated. It was found that the coated samples indicate significantly higher oxidation and corrosion resistance compared to uncoated Ni super alloy. This is mainly due to the formation of protective Cr2O3 and Al2O3 layers on the coating surface. With the increase of Al content, the coatings exhibited improved oxidation resistance. The formation of thin and adherent Al2O3 scale on the surface of Al rich coating is the reason for its better oxidation behavior. The detailed structures of the oxide scales and the interdiffusion between coating and substrate were studied using energy dispersive X-ray spectroscopy-analysis.}, language = {en} } @inproceedings{WeissMeissner, author = {Weiß, Sabine and Meissner, Andreas}, title = {Austenitic high nitrogen steel: An alternative material for coronary stents?}, series = {8th World Biomaterials Congress 2008, Amsterdam, 28 May - 1 June 2008}, booktitle = {8th World Biomaterials Congress 2008, Amsterdam, 28 May - 1 June 2008}, publisher = {Curran Associates Inc.}, address = {Red Hook, NY}, isbn = {978-1-61567-080-2}, language = {en} } @misc{FischerBurgaudAmeretal., author = {Fischer, Annette and Burgaud, D. and Amer, A. E. and Weiß, Sabine}, title = {Fatigue aspects of the generation of nanoparticles during wear of biomedical alloys}, series = {8th World Biomaterials Congress 2008, Amsterdam, 28 May - 1 June 2008}, journal = {8th World Biomaterials Congress 2008, Amsterdam, 28 May - 1 June 2008}, publisher = {Curran Associates Inc.}, address = {Red Hook, NY}, isbn = {978-1-61567-080-2}, language = {en} } @misc{KazakWeiss, author = {Kazak, Fedor and Weiß, Sabine}, title = {Analysis of the Frequency as an Integral Method for the Testing of Anisotropic 3D Sheet Metal Structure}, series = {Materials Testing}, volume = {56}, journal = {Materials Testing}, number = {9}, issn = {0025-5300}, pages = {656 -- 661}, language = {en} } @misc{RanjbarnodehWeissHankeetal., author = {Ranjbarnodeh, Eslam and Weiß, Sabine and Hanke, Stefanie and Fischer, Alfons}, title = {EBSD characterization of the effect of welding parameters on HAZ of AlSl409}, series = {Journal of Mining and Metallurgy : B, Metallurgy}, volume = {48}, journal = {Journal of Mining and Metallurgy : B, Metallurgy}, number = {1}, pages = {115 -- 121}, language = {en} } @misc{RanjbarnodehHankeWeissetal., author = {Ranjbarnodeh, Eslam and Hanke, Stefanie and Weiß, Sabine and Fischer, Alfons}, title = {Effect of welding parameters on the heataffected zone of AlSI409 ferritic stainless steel}, series = {International Journal of Minerals, Metallurgy and Materials}, volume = {19}, journal = {International Journal of Minerals, Metallurgy and Materials}, number = {10}, issn = {1869-103X}, pages = {923 -- 929}, language = {en} } @misc{FischerMeissnerWeiss, author = {Fischer, Annette and Meissner, Andreas and Weiß, Sabine}, title = {Microstructural peculiarities and mechanical properties of coronary stents}, series = {Nonlocal Modelling of Failure of Materials, proceedings of an international workshop, University of Wuppertal, June 2007}, journal = {Nonlocal Modelling of Failure of Materials, proceedings of an international workshop, University of Wuppertal, June 2007}, editor = {Yuan, Huang and Wittmann, Folker H.}, publisher = {Aedificatio Publ.}, address = {Freiburg}, isbn = {978-3-931681-87-6}, pages = {91 -- 104}, language = {en} } @phdthesis{Weiss, author = {Weiß, Sabine}, title = {Mikrostruktur- und Mikrotexturentwicklung bei der zyklischen Hochtemperaturverformung reiner kubisch-fl{\"a}chenzentrierter Metalle}, publisher = {Shaker}, address = {Aachen}, isbn = {3-8265-3372-0}, pages = {IV, 152}, language = {de} } @misc{HeringKailEckertetal., author = {Hering, Daniel and Kail, Jochem and Eckert, Sabine and Gerhard, Marc and Meyer, Elisabeth I. and Mutz, Michael and Reich, Michael and Weiss, Ilga}, title = {Coarse Woody Debris Quantity and Distribution in Central European Streams}, series = {International Review of Hydrobiology}, volume = {85}, journal = {International Review of Hydrobiology}, number = {1}, issn = {1522-2632}, doi = {10.1002/(SICI)1522-2632(200003)85:1<5::AID-IROH5>3.0.CO;2-X}, pages = {5 -- 23}, language = {en} } @misc{BolzOehringLindemannetal., author = {Bolz, Sebastian and Oehring, Michael and Lindemann, Janny and Pyczak, Florian and Paul, Jonathan and Stark, Andreas and Lippmann, Thomas and Roth-Fagaraseanu, Dan and Schreyer, Andreas and Weiß, Sabine and Schr{\"u}fer, Susanne}, title = {Microstructure and mechanical properties of a forged beta-solidifying gamma TiAl alloy in different heat treatment conditions}, series = {Intermetallics}, volume = {2015}, journal = {Intermetallics}, number = {58}, pages = {71 -- 83}, language = {en} } @misc{SchulzeSeidlitzKoenigetal., author = {Schulze, Marcus and Seidlitz, Holger and K{\"o}nig, Franziska and Weiß, Sabine}, title = {Tribological Investigations of PVD Coated Multi-Layer Constructions}, series = {Journal of Materials Science Research}, volume = {5}, journal = {Journal of Materials Science Research}, number = {1}, issn = {1927-0585}, doi = {10.5539/jmsr.v5n1p97}, pages = {97 -- 106}, abstract = {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.}, language = {en} } @misc{OehringLindemannPyczaketal., author = {Oehring, Michael and Lindemann, Janny and Pyczak, Florian and Paul, Jonathan and Stark, Andreas and Lippmann, Thomas and Schr{\"u}fer, Susanne and Roth-Fagaraseanu, Dan and Schreyer, Andreas and Weiß, Sabine}, title = {Microstructure and mechanical properties of a forged β-solidifying γ TiAl alloy in different heat treatment conditions}, series = {Intermetallics}, volume = {2015}, journal = {Intermetallics}, number = {58}, issn = {0966-9795}, doi = {10.1016/j.intermet.2014.11.008}, pages = {71 -- 83}, abstract = {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.}, language = {en} } @misc{KazakWeiss, author = {Kazak, Fedor and Weiß, Sabine}, title = {Test procedure for fatigue investigations regarding structured sheet metal joints}, series = {Materials Testing}, volume = {58}, journal = {Materials Testing}, number = {2}, issn = {0025-5300}, pages = {109 -- 116}, abstract = {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.}, language = {en} } @misc{KazakWeiss, author = {Kazak, Fedor and Weiß, Sabine}, title = {Comparability of structured and flat reference specimens made of thin sheet metal}, series = {Materials Testing}, volume = {57}, journal = {Materials Testing}, number = {6}, issn = {0025-5300}, doi = {10.3139/120.110748}, pages = {567 -- 573}, abstract = {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.}, language = {en} } @misc{WeissMitevski, author = {Weiß, Sabine and Mitevski, Bojan}, title = {Microstructure and Deformation of Coronary Stents from CoCr-Alloys with Different Designs}, series = {Materials}, volume = {8}, journal = {Materials}, number = {5}, issn = {1996-1944}, doi = {10.3390/ma8052467}, pages = {2467 -- 2479}, abstract = {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.}, language = {en} } @misc{NaveedFloresRenteriaNebeletal., author = {Naveed, Muhammad and Flores Renteria, Arturo and Nebel, Daniel and Weiß, Sabine}, title = {Study of high velocity solid particle erosion behaviour of Ti2AlC MAX phase coatings}, series = {Wear}, volume = {2015}, journal = {Wear}, number = {342-343}, issn = {0043-1648}, doi = {10.1016/j.wear.2015.09.014}, pages = {391 -- 397}, abstract = {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.}, language = {en} } @misc{NaveedObrosovWeiss, author = {Naveed, Muhammad and Obrosov, Aleksei and Weiß, Sabine}, title = {Investigation of the wear resistance properties of Cr/CrN multilayer coatings against sand erosion}, series = {Conference Papers in Science}, volume = {2015}, journal = {Conference Papers in Science}, doi = {10.1155/2015/873543}, pages = {1 -- 10}, abstract = {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.}, language = {en} } @incollection{MlikotaSchmauderMitevskietal., author = {Mlikota, Marjo and Schmauder, Siegfried and Mitevski, Bojan and Weiß, Sabine}, title = {Scientific Multiscale and Multidisciplinary Analysis of Deformation and Damage in the Case of Oligocrystalline Structures}, series = {Computer Science and Engineering Technology}, booktitle = {Computer Science and Engineering Technology}, editor = {Deng, Jiamei and Liu, Quingjun}, publisher = {World Scientific Publishing}, address = {Singapore}, isbn = {978-981-4651-00-4}, pages = {113 -- 118}, abstract = {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.}, language = {en} } @misc{SchulzeSeidlitzKoenigetal., author = {Schulze, Marcus and Seidlitz, Holger and K{\"o}nig, Franziska and Weiß, Sabine}, title = {Nanoindentation measurements of PVD coated multilayer constructions}, series = {Journal of Achievements in Materials and Manufacturing Engineering}, volume = {72}, journal = {Journal of Achievements in Materials and Manufacturing Engineering}, number = {2}, issn = {1734-8412}, pages = {53 -- 60}, abstract = {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.}, language = {en} } @misc{SchulzeSeidlitzKoenigetal., author = {Schulze, Marcus and Seidlitz, Holger and K{\"o}nig, Franziska and Weiß, Sabine}, title = {Highly wear resistant PVD coatings for CFRP based multi-layer construction}, series = {11th International Scientific-Technical Conference on Advances in Plastics Technology (APT'15)}, journal = {11th International Scientific-Technical Conference on Advances in Plastics Technology (APT'15)}, address = {Gliwice}, isbn = {978-83-63555-47-4}, language = {en} } @misc{StechowIvanovaNaveedetal., author = {Stechow, Richard and Ivanova, Irina and Naveed, Muhammad and Weiß, Sabine}, title = {Sample Preparation of Worn Surfaces for EBSD Analysis}, series = {Praktische Metallographie}, volume = {53}, journal = {Praktische Metallographie}, number = {6}, issn = {0032-678x}, doi = {10.3139/147.110401}, pages = {352 -- 359}, language = {en} } @misc{NaveedStechowBolzetal., author = {Naveed, Muhammad and Stechow, Richard and Bolz, Sebastian and Hobusch, Katharina and Weiß, Sabine}, title = {Solid Particle Erosion of Heat Treated TNB-V4 at Ambient and Elevated Temperatures}, series = {International Journal of Chemical, Molecular, Nuclear, Materials and Metallurgical Engineering}, volume = {10}, journal = {International Journal of Chemical, Molecular, Nuclear, Materials and Metallurgical Engineering}, number = {5}, pages = {571 -- 576}, language = {en} } @misc{KazakSchleussOssenbrinketal., author = {Kazak, Fedor and Schleuß, Leander and Ossenbrink, Ralf and Michailov, Vesselin and Weiß, Sabine}, title = {Particularities of testing structured sheet metals in 3-point bending tests}, series = {Materials Testing}, volume = {58}, journal = {Materials Testing}, number = {6}, issn = {0025-5300}, doi = {10.3139/120.110883}, pages = {495 -- 500}, abstract = {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.}, language = {en} } @misc{NaveedFloresRenteriaWeiss, author = {Naveed, Muhammad and Flores Renteria, Arturo and Weiß, Sabine}, title = {Role of alloying elements during thermocyclic oxidation of β/γ-TiAl alloys at high temperatures}, series = {Journal of Alloys and Compounds}, volume = {691}, journal = {Journal of Alloys and Compounds}, issn = {0925-8388}, doi = {10.1016/j.jallcom.2016.08.259}, pages = {489 -- 497}, abstract = {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.}, language = {en} } @misc{BambachSizovaBolzetal., author = {Bambach, Markus and Sizova, Irina and Bolz, Sebastian and Weiß, Sabine}, title = {Devising Strain Hardening Models Using Kocks-Mecking Plots - A Comparison of Model Development for Titanium Aluminides and Case Hardening Steel}, series = {Metals}, volume = {6}, journal = {Metals}, number = {9}, issn = {2075-4701}, doi = {10.3390/met6090204}, pages = {204}, language = {en} } @misc{NaveedObrosovZaketal., author = {Naveed, Muhammad and Obrosov, Aleksei and Zak, Andrzej and Dudzinski, Wlodzimierz and Volinsky, Alex A. and Weiß, Sabine}, title = {Sputtering Power Effects on Growth and Mechanical Properties of Cr2AlC MAX Phase Coatings}, series = {Metals}, volume = {6}, journal = {Metals}, number = {11}, issn = {2075-4701}, doi = {10.3390/met6110265}, pages = {265}, abstract = {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.}, language = {en} } @misc{ObrosovNaveedVolinskyetal., author = {Obrosov, Aleksei and Naveed, Muhammad and Volinsky, Alex A. and Weiß, Sabine}, title = {Substrate Frequency Effects on CrxN Coatings Deposited by DC Magnetron Sputtering}, series = {Journal of Materials Engineering and Performance}, volume = {26}, journal = {Journal of Materials Engineering and Performance}, number = {1}, issn = {1544-1024}, doi = {10.1007/s11665-016-2426-4}, pages = {366 -- 373}, abstract = {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.}, language = {en} } @misc{ObrosovGulyaevZaketal., author = {Obrosov, Aleksei and Gulyaev, Roman and Zak, Andrzej and Ratzke, Markus and Naveed, Muhammad and Dudzinski, Wlodzimierz and Weiß, Sabine}, title = {Chemical and Morphological Characterization of Magnetron Sputtered at Different Bias Voltages Cr-Al-C Coatings}, series = {Materials}, volume = {10}, journal = {Materials}, number = {2}, issn = {1996-1944}, doi = {10.3390/ma10020156}, pages = {156}, abstract = {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.}, language = {en} } @misc{ObrosovGulyaevRatzkeetal., author = {Obrosov, Aleksei and Gulyaev, Roman and Ratzke, Markus and Volinsky, Alex A. and Bolz, Sebastian and Naveed, Muhammad and Weiß, Sabine}, title = {XPS and AFM Investigations of Ti-Al-N Coatings Fabricated Using DC Magnetron Sputtering at Various Nitrogen Flow Rates and Deposition Temperatures}, series = {Metals}, volume = {7}, journal = {Metals}, number = {2}, issn = {2075-4701}, doi = {10.3390/met7020052}, pages = {52}, abstract = {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.}, language = {en} } @inproceedings{SchulzeSeidlitzKoenigetal., author = {Schulze, Marcus and Seidlitz, Holger and K{\"o}nig, Franziska and Weiß, Sabine}, title = {Nanoindentation measurements of PVD coated multilayer constructions}, series = {Programme and proceedings of the 22nd Winter International Scintific Conference on Achivements in Mechanical and Materials Engineering (AMME'15), Gliwice - Zakopane (Poland), 2015}, booktitle = {Programme and proceedings of the 22nd Winter International Scintific Conference on Achivements in Mechanical and Materials Engineering (AMME'15), Gliwice - Zakopane (Poland), 2015}, editor = {Dobrzański, Leszek A.}, publisher = {Gliwice}, address = {International OCSCO World Press}, isbn = {978-83-63553-39-5}, language = {en} } @misc{ObrosovSutyginaVolinskyetal., author = {Obrosov, Aleksei and Sutygina, Alina and Volinsky, Alex A. and Manakhov, Anton and Weiß, Sabine and Kashkarov, Egor B.}, title = {Effect of Hydrogen Exposure on Mechanical and Tribological Behavior of CrₓN Coatings Deposited at Different Pressures on IN718}, series = {Materials}, volume = {10}, journal = {Materials}, number = {5}, issn = {1996-1944}, doi = {10.3390/ma10050563}, pages = {563}, abstract = {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.}, language = {en} } @inproceedings{ObrosovKashkarovWeissetal., author = {Obrosov, Aleksei and Kashkarov, Egor B. and Weiß, Sabine and Volinsky, Alex A.}, title = {Mechanical and tribological behaviour of hydrogenated CrxN coatings deposited at different pressure and voltages on IN718}, series = {American Advanced Materials Congress 2016}, booktitle = {American Advanced Materials Congress 2016}, editor = {Tiwari, Ashutosh}, publisher = {VBRI Press}, address = {Link{\"o}ping}, isbn = {978-91-88252-03-6}, abstract = {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.}, language = {en} } @misc{ObrosovNaveedKruppetal., author = {Obrosov, Aleksei and Naveed, Muhammad and Krupp, Ulrich and Solovev, Mikhail and Weiß, Sabine}, title = {Investigation of TiAlN HiPIMS coating deposited on the newly developed Ni-based superalloy AD730}, abstract = {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.}, language = {en} } @misc{ObrosovNaveedWeiss, author = {Obrosov, Aleksei and Naveed, Muhammad and Weiß, Sabine}, title = {Effect of pulse time on structure and mechanical properties of HPPMS deposited AlTiN coatings}, abstract = {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.}, language = {en} } @inproceedings{BambachSizovaBolzetal., author = {Bambach, Markus and Sizova, Irina and Bolz, Sebastian and Weiß, Sabine}, title = {Development of a dynamic recrystallization model for a β-solidifying titanium aluminide alloy using Kocks-Mecking plots}, series = {ESAFORM 2016, proceedings of the 19th International ESAFORM Conference on Material Forming, Nantes, France, 27-29 April 2016}, booktitle = {ESAFORM 2016, proceedings of the 19th International ESAFORM Conference on Material Forming, Nantes, France, 27-29 April 2016}, publisher = {AIP Publishing}, address = {Melville, New York}, isbn = {978-0-7354-1427-3}, doi = {10.1063/1.4963545}, pages = {160002-1 -- 160002-7}, language = {en} } @misc{KashkarovNikitenkovSutyginaetal., author = {Kashkarov, Egor B. and Nikitenkov, Nikolay and Sutygina, Alina and Laptev, Roman and Bordulev, Yuriy and Obrosov, Aleksei and Liedke, Maciej O. and Zak, Andrzej and Weiß, Sabine}, title = {Microstructure, defect structure and hydrogen trapping in zirconium alloy Zr-1Nb treated by plasma immersion Ti ion implantation and deposition}, series = {Journal of Alloys and Compounds}, volume = {732}, journal = {Journal of Alloys and Compounds}, issn = {0925-8388}, doi = {10.1016/j.jallcom.2017.10.151}, pages = {80 -- 87}, abstract = {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.}, language = {en} } @misc{ShulepovKashkarovStepanovetal., author = {Shulepov, Ivan A. and Kashkarov, Egor B. and Stepanov, Igor B. and Syrtanov, Maxim S. and Sutygina, Alina and Shanenkov, Ivan and Obrosov, Aleksei and Weiß, Sabine}, title = {The Formation of Composite Ti-Al-N Coatings Using Filtered Vacuum Arc Deposition with Separate Cathodes}, series = {Metals}, volume = {7}, journal = {Metals}, number = {11}, issn = {2075-4701}, doi = {10.3390/met7110497}, pages = {13}, abstract = {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.}, language = {en} } @misc{SeverinNaveedWeiss, author = {Severin, Stefanie and Naveed, Muhammad and Weiß, Sabine}, title = {Effect of HPPMS pulse-frequency on plasma discharge and deposited AlTiN coating properties}, series = {Advances in Materials Science and Engineering}, volume = {2017}, journal = {Advances in Materials Science and Engineering}, issn = {1687-8442}, pages = {18}, abstract = {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.}, language = {en} } @misc{DonchevaBambachBambachSviridovetal., author = {Doncheva Bambach, Margarita and Bambach, Markus and Sviridov, Alexander and Weiß, Sabine}, title = {New process chains involving additive manufacturing and metal forming - a chance for saving energy?}, series = {Procedia Engineering}, volume = {207}, journal = {Procedia Engineering}, issn = {1877-7058}, doi = {10.1016/j.proeng.2017.10.1049}, pages = {1176 -- 1181}, language = {en} } @misc{ObrosovSutyginaManakhovetal., author = {Obrosov, Aleksei and Sutygina, Alina and Manakhov, Anton and Bolz, Sebastian and Weiß, Sabine and Kashkarov, Egor B.}, title = {Oxidation Behavior of Zr-1Nb Corroded in Air at 400 °C after Plasma Immersion Titanium Implantation}, series = {Metals}, volume = {8}, journal = {Metals}, number = {1}, issn = {2075-4701}, doi = {10.3390/met8010027}, pages = {16}, abstract = {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.}, language = {en} } @misc{KashkarovNikitenkovSutyginaetal., author = {Kashkarov, Egor B. and Nikitenkov, Nikolay and Sutygina, Alina and Obrosov, Aleksei and Manakhov, Anton and Polčak, Josef and Weiß, Sabine}, title = {Hydrogen absorption by Ti-implanted Zr-1Nb alloy}, series = {International journal of hydrogen energy}, volume = {43}, journal = {International journal of hydrogen energy}, number = {4}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2017.12.003}, pages = {2484 -- 2491}, abstract = {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.}, language = {en} } @misc{KashkarovObrosovSutyginaetal., author = {Kashkarov, Egor B. and Obrosov, Aleksei and Sutygina, Alina and Uludintceva, Elena and Mitrofanov, Andrei and Weiß, Sabine}, title = {Hydrogen Permeation, and Mechanical and Tribological Behavior, of CrNx Coatings Deposited at Various Bias Voltages on IN718 by Direct Current Reactive Sputtering}, series = {Coatings}, volume = {8}, journal = {Coatings}, number = {2}, issn = {2079-6412}, doi = {10.3390/coatings8020066}, pages = {12}, abstract = {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.}, language = {en} } @misc{EvdokimovObrosovOssenbrinketal., author = {Evdokimov, Anton and Obrosov, Aleksei and Ossenbrink, Ralf and Weiß, Sabine and Michailov, Vesselin}, title = {Mechanical properties of dissimilar steel-aluminum weld}, series = {Materials Science and Engineering: A}, volume = {Volume 722}, journal = {Materials Science and Engineering: A}, issn = {0921-5093}, doi = {https://doi.org/10.1016/j.msea.2018.03.019}, pages = {242 -- 254}, abstract = {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.}, language = {en} } @misc{ObrosovSutyginaKashkarovetal., author = {Obrosov, Aleksei and Sutygina, Alina and Kashkarov, Egor B. and Weiß, Sabine}, title = {Oxidation behavior of Zr-1Nb in air at 400°C after Titanium Plasma Immersion Ion Implantation}, pages = {1}, abstract = {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.}, language = {en} } @misc{AbangWeissKrautz, author = {Abang, Roger Atini and Weiß, Sabine and Krautz, Hans Joachim}, title = {Impact of increased power plant cycling on the oxidation and corrosion of coal-fired superheater materials}, series = {Fuel}, volume = {2018}, journal = {Fuel}, number = {220}, issn = {0016-2361}, doi = {10.1016/j.fuel.2018.02.047}, pages = {521 -- 534}, abstract = {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.}, language = {en} } @misc{SanthanakrishnanBalakrishnanSeidlitzWeiss, author = {Santhanakrishnan Balakrishnan, Venkateswaran and Seidlitz, Holger and Weiß, Sabine}, title = {Layup Configuration Effect on Notch Residual Strength in Composite Laminates}, series = {Materials}, volume = {11}, journal = {Materials}, number = {2}, issn = {1996-1944}, doi = {10.3390/ma11020308}, pages = {12}, abstract = {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.}, language = {en} } @misc{KashkarovRyabchikovKurochkinetal., author = {Kashkarov, Egor B. and Ryabchikov, Alexander I. and Kurochkin, Alexander and Syrtanov, Maxim S. and Shevelev, Alexey and Obrosov, Aleksei and Weiß, Sabine}, title = {Hydrogen Interaction with Deep Surface Modified Zr-1Nb Alloy by High Intensity Ti Ion Implantation}, series = {Metals}, volume = {8}, journal = {Metals}, number = {12}, issn = {2075-4701}, doi = {10.3390/met8121081}, abstract = {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.}, language = {en} } @misc{GuntherYasenchukChekalkinetal., author = {Gunther, Victor and Yasenchuk, Yuri and Chekalkin, Timofey and Marchenko, Ekaterina and Gunther, Sergey and Baigonakova, Gulsharat and Hodorenko, Valentina and Kang, Ji-hoon and Weiß, Sabine and Obrosov, Aleksei}, title = {Formation of pores and amorphous-nanocrystalline phases in porous TiNi alloys made by self-propagating high-temperature synthesis (SHS)}, series = {Advanced Powder Technology}, volume = {30}, journal = {Advanced Powder Technology}, number = {4}, issn = {0921-8831}, doi = {10.1016/j.apt.2018.12.011}, pages = {673 -- 680}, abstract = {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.}, language = {en} } @misc{YasenchukGuntherMarchenkoetal., author = {Yasenchuk, Yuri and Gunther, Victor and Marchenko, Ekaterina and Chekalkin, Timofey and Baigonakova, Gulsharat and Hodorenko, Valentina and Gunther, Sergey and Kang, Ji-hoon and Weiß, Sabine and Obrosov, Aleksei}, title = {Formation of mineral phases in self-propagating high-temperature synthesis (SHS) of porous TiNi alloy}, series = {Materials Research Express}, volume = {6}, journal = {Materials Research Express}, number = {5}, issn = {2053-1591}, doi = {10.1088/2053-1591/ab01a1}, pages = {13}, abstract = {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.}, language = {en} } @misc{FellahHezilDjellabietal., author = {Fellah, Mamoun and Hezil, Naouel and Djellabi, Ridha and Samad, Mohammed Abdul and Touhami, Mohamed Zine and Montagne, Alex and Iost, Alain and Obrosov, Aleksei and Weiß, Sabine}, title = {Rapid and enhanced recovery of poly-dispersed nonionic surfactant (TX-100) from organic mediums using dehydrated and rehydrated kaolin}, series = {Applied Clay Science}, volume = {177}, journal = {Applied Clay Science}, issn = {0169-1317}, doi = {10.1016/j.clay.2019.05.004}, pages = {43 -- 50}, abstract = {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.}, language = {en} } @misc{SanthanakrishnanBalakrishnanObrosovKukeetal., author = {Santhanakrishnan Balakrishnan, Venkateswaran and Obrosov, Aleksei and Kuke, Felix and Seidlitz, Holger and Weiß, Sabine}, title = {Influence of metal surface preparation on the flexural strength and impact damage behaviour of thermoplastic FRP reinforced metal laminate made by press forming}, series = {Composites Part B: Engineering}, volume = {173}, journal = {Composites Part B: Engineering}, issn = {1359-8368}, doi = {10.1016/j.compositesb.2019.05.094}, abstract = {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.}, language = {en} } @misc{FellahHezilSamadetal., author = {Fellah, Mamoun and Hezil, Naouel and Samad, Mohammed Abdul and Montagne, Alex and Kosman, Stephania and Megias, Alberto and Iost, Alain and Obrosov, Aleksei and Weiß, Sabine}, title = {Biotribocorrosion behaviour of newly developed nanostructured near β-types Titanium based Alloys for Biomedical Applications}, series = {nanoMAT2019 - 2nd International Conference on Nanomaterials and Their Applications}, journal = {nanoMAT2019 - 2nd International Conference on Nanomaterials and Their Applications}, pages = {170}, abstract = {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.}, language = {en} } @misc{ObrosovYasenchukMarchenkoetal., author = {Obrosov, Aleksei and Yasenchuk, Yuri and Marchenko, Ekaterina and Gunther, Victor and Radkevich, Andrey and Kokorev, Oleg and Gunther, Sergey and Baigonakova, Gulsharat and Hodorenko, Valentina and Chekalkin, Timofey and Kang, Ji-hoon and Weiß, Sabine}, title = {Biocompatibility and Clinical Application of Porous TiNi Alloys Made by Self-Propagating High-Temperature Synthesis (SHS)}, series = {Materials}, volume = {12}, journal = {Materials}, number = {15}, issn = {1996-1944}, doi = {10.3390/ma12152405}, pages = {25}, abstract = {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.}, language = {en} } @misc{BouaksaFellahHeziletal., author = {Bouaksa, Fethia and Fellah, Mamoun and Hezil, Naouel and Djellabi, Ridha and Touhami, Mohamed Zine and Iost, Alain and Montagne, Alex and Kosman, Stephania and Weiß, Sabine}, title = {Effect of Thermocyclic Treatment with Different Cooling Rates on the Mechanical Characteristics of 42CD4 Low-Alloy Steel}, series = {Defect and Diffusion Forum}, volume = {397}, journal = {Defect and Diffusion Forum}, issn = {1662-9507}, doi = {10.4028/www.scientific.net/DDF.397.169}, pages = {169 -- 178}, abstract = {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.}, language = {en} } @misc{FellahHezilSamadetal., author = {Fellah, Mamoun and Hezil, Naouel and Samad, Mohammed Abdul and Djellabi, Ridha and Montagne, Alex and Mejias, Alberto and Kossman, Stephania and Iost, Alain and Purnama, Agung and Obrosov, Aleksei and Weiß, Sabine}, title = {Effect of Molybdenum Content on Structural, Mechanical, and Tribological Properties of Hot Isostatically Pressed β-Type Titanium Alloys for Orthopedic Applications}, series = {Journal of Materials Engineering and Performance}, volume = {28}, journal = {Journal of Materials Engineering and Performance}, number = {10}, issn = {1059-9495}, doi = {10.1007/s11665-019-04348-w}, pages = {5988 -- 5999}, abstract = {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.}, language = {en} } @misc{ObrosovKashkarovSharmaetal., author = {Obrosov, Aleksei and Kashkarov, Egor B. and Sharma, A. and Weiß, Sabine}, title = {Microstructure and defect structure of Zr-1Nb alloy deep surface modified by high Intensity Ti Ion implantation}, series = {MC Microscopy Conference, 01-05 September 2019, Berlin, Abstracts}, journal = {MC Microscopy Conference, 01-05 September 2019, Berlin, Abstracts}, address = {Berlin}, pages = {86}, abstract = {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.}, language = {en} } @misc{FellahHezilDekhiletal., author = {Fellah, Mamoun and Hezil, Naouel and Dekhil, Leila and Samad, Mohammed Abdul and Djellabi, Ridha and Kosman, Stephania and Montagne, Alex and Iost, Alain and Obrosov, Aleksei and Weiß, Sabine}, title = {Effect of sintering temperature on structure and tribological properties of nanostructured Ti-15Mo alloy for biomedical applications}, series = {Transactions of Nonferrous Metals Society of China}, volume = {29}, journal = {Transactions of Nonferrous Metals Society of China}, number = {11}, issn = {1003-6326}, doi = {10.1016/S1003-6326(19)65137-X}, pages = {2310 -- 2320}, abstract = {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.}, language = {en} } @misc{ErmilovaKazakWeiss, author = {Ermilova, Evgeniia and Kazak, Fedor and Weiß, Sabine}, title = {Stability of structured sheet metals during buckling}, series = {Materials Testing}, volume = {61}, journal = {Materials Testing}, number = {10}, issn = {2195-8572}, doi = {10.3139/120.111403}, pages = {929 -- 935}, abstract = {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.}, language = {en} } @misc{FellahHezilDekhiletal., author = {Fellah, Mamoun and Hezil, Naouel and Dekhil, Leila and Samad, Mohammed Abdul and Montagne, Alex and Mejias, Alberto and Iost, Alain and Obrosov, Aleksei and Weiß, Sabine}, title = {Structural characterization of developed near β-Type Titanium Alloys (Ti-25NbxZr) for biomedical Applications}, series = {3rd International Conference on Mechanics and Materials : ICMM'2019 11-12 November 2019. Setif, Algeria, Abstracts book}, journal = {3rd International Conference on Mechanics and Materials : ICMM'2019 11-12 November 2019. Setif, Algeria, Abstracts book}, address = {Setif, Algeria}, pages = {224 -- 225}, abstract = {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.}, language = {en} } @misc{KhalilFellahHeziletal., author = {Khalil, S. and Fellah, Mamoun and Hezil, Naouel and Smata, L. and Montagne, Alex and Mejias, Alberto and Kossman, Stephania and Iost, Alain and Obrosov, Aleksei and Weiß, Sabine}, title = {Synth{\`e}se et caract{\´e}risation structurale d'un compos{\´e} nanostructur{\´e} de Ti, Mo et Zr pour applications biom{\´e}dicales}, series = {3rd International Conference on Mechanics and Materials : ICMM'2019 11-12 November 2019. Setif, Algeria, Abstracts book}, journal = {3rd International Conference on Mechanics and Materials : ICMM'2019 11-12 November 2019. Setif, Algeria, Abstracts book}, address = {Setif, Algeria}, pages = {243 -- 244}, abstract = {Le milieu m{\´e}dical est un perp{\´e}tuel demandeur de biomat{\´e}riaux compatibles surtout en orthop{\´e}die. Effectivement le nombre important d'arthroplasties effectu{\´e}es chaque ann{\´e}e ne cesse d'augmenter dans le monde, non seulement du fait vieillissement de la population ({\`a} partir de 65 ans), mais aussi de demandes de patients plus jeunes entre 45 ans et 55 ans. Actuellement, les compos{\´e}s {\`a} base de titane Ti sont largement utilis{\´e}s comme des biomat{\´e}riaux pour leur biocompatibilit{\´e}, leur r{\´e}sistance {\`a} la corrosion et leur faible module d'{\´e}lasticit{\´e}. Le molybd{\`e}ne et le zirconium sont parmi les meilleurs {\´e}l{\´e}ments alli{\´e}s parce qu'ils sont non toxiques et non allergiques et offrent d'excellentes propri{\´e}t{\´e}s. De plus,Le Zr peut augmenter la trempabilit{\´e} et la r{\´e}sistance {\`a} la corrosion de l'alliage . Mo est un {\´e}l{\´e}ment fort stabilisant pour la phase des alliages de titane et les alliages {\`a} base de Ti-Mo pr{\´e}sentent des propri{\´e}t{\´e}s m{\´e}caniques ad{\´e}quates compatibilit{\´e} et bonne cyto-compatibilit{\´e} . Par cons{\´e}quent, le syst{\`e}me Ti-Mo-Zr, qui a montr{\´e} une bonnes performances et de magnifiques perspectives dans l'application de biomat{\´e}riaux, a {\´e}t{\´e} intensivement{\´e}tudi{\´e} [1,2,3]. Cependant, les alliages de Ti largement utilis{\´e}s, 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 lib{\´e}rer de l'aluminium toxique (Al) et les Ions de vanadium (V) in vivo, ce qui peut causer des probl{\`e}mes de sant{\´e}, comme la maladie d'Alzheimer et la neuropathie[4].La m{\´e}tallurgie des poudres (MP), y compris la m{\´e}thode de mixture des composants en poudre, qui consiste {\`a} fritter titane en poudre ou ses m{\´e}langes avec d'autres composants en poudre, est un proc{\´e}d{\´e} {\´e}conomique {\`a} moindre cout. La nanotechnologie est intervenue dans la structuration des biomat{\´e}riaux {\`a} l'{\´e}chelle nanom{\´e}trique (entre1nmet 100 nm) par soucis d'am{\´e}lioration des propri{\´e}t{\´e}s m{\´e}canique surtout le module de Young.}, language = {fr} } @misc{ShapovalovGaalHoenigetal., author = {Shapovalov, Oleg and Gaal, Mate and H{\"o}nig, Gerald and Gradt, Thomas and Weiß, Sabine}, title = {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}, series = {Proceedings of the 23rd International Congress on Acoustics : integrating 4th EAA Euroregio 2019 : 9-13 September 2019 in Aachen, Germany}, volume = {2019}, journal = {Proceedings of the 23rd International Congress on Acoustics : integrating 4th EAA Euroregio 2019 : 9-13 September 2019 in Aachen, Germany}, editor = {Ochmann, Martin and Vorl{\"a}nder, Michael and Fels, Janina}, address = {Aachen}, isbn = {978-3-939296-15-7}, issn = {2226-7808}, doi = {10.18154/RWTH-CONV-239953}, pages = {4754 -- 4760}, abstract = {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.}, language = {en} } @misc{MarchenkoYasenchukGuntheretal., author = {Marchenko, Ekaterina and Yasenchuk, Yuri and Gunther, Sergey and Baigonakova, Gulsharat and Gunther, Victor and Chekalkin, Timofey and Weiß, Sabine and Obrosov, Aleksei and Dubovikov, Kirill}, title = {Structural-phase surface composition of porous TiNi produced by SHS}, series = {Materials Research Express}, volume = {6}, journal = {Materials Research Express}, number = {11}, issn = {2053-1591}, doi = {10.1088/2053-1591/ab4e32}, pages = {12}, abstract = {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.}, language = {en} } @misc{FellahHezilSamadetal., author = {Fellah, Mamoun and Hezil, Naouel and Samad, Mohammed Abdul and Touhami, Mohamed Zine and Montagne, Alex and Iost, Alain and Obrosov, Aleksei and Weiß, Sabine}, title = {Preliminary investigation on the bio-tribocorrosion behavior of porous nanostructured β-type titanium based biomedical alloys}, series = {Materials Letters}, volume = {257}, journal = {Materials Letters}, issn = {0167-577X}, doi = {10.1016/j.matlet.2019.126755}, pages = {4}, abstract = {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.}, language = {en} } @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} }