TY - JOUR AU - Krüger, Jan Tobias AU - Hoyer, Kay-Peter AU - Schaper, Mirko ID - 41509 JF - Materials Letters KW - Mechanical Engineering KW - Mechanics of Materials KW - Condensed Matter Physics KW - General Materials Science SN - 0167-577X TI - Bioresorbable AgCe and AgCeLa alloys for adapted Fe-based implants VL - 306 ER - TY - JOUR AU - Andreiev, Anatolii AU - Hoyer, Kay-Peter AU - Dula, Dimitri AU - Hengsbach, Florian AU - Haase, Michael AU - Gierse, Jan AU - Zimmer, Detmar AU - Tröster, Thomas AU - Schaper, Mirko ID - 23898 JF - Journal of Materials Processing Technology SN - 0924-0136 TI - Soft-magnetic behavior of laser beam melted FeSi3 alloy with graded cross-section ER - TY - JOUR AB - AbstractWithin this research, the multiscale microstructural evolution before and after the tensile test of a FeCo alloy is addressed. X-ray µ-computer tomography (CT), electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM) are employed to determine the microstructure on different length scales. Microstructural evolution is studied by performing EBSD of the same area before and after the tensile test. As a result, $$\langle$$ 001$$\rangle$$ ||TD, $$\langle$$ 011$$\rangle$$ ||TD are hard orientations and $$\langle$$ 111$$\rangle$$ ||TD is soft orientations for deformation accommodation. It is not possible to predict the deformation of a single grain with the Taylor model. However, the Taylor model accurately predicts the orientation of all grains after deformation. {123}$$\langle$$ 111$$\rangle$$ is the most active slip system, and {112}$$\langle$$ 111$$\rangle$$ is the least active slip system. Both EBSD micrographs show grain subdivision after tensile testing. TEM images show the formation of dislocation cells. Correlative HRTEM images show unresolved lattice fringes at dislocation cell boundaries, whereas resolved lattice fringes are observed at dislocation cell interior. Since Schmid’s law is unable to predict the deformation behavior of grains, the boundary slip transmission accurately predicts the grain deformation behavior. AU - Pramanik, Sudipta AU - Tasche, Lennart AU - Hoyer, Kay-Peter AU - Schaper, Mirko ID - 41517 IS - 11 JF - Journal of Materials Engineering and Performance KW - Mechanical Engineering KW - Mechanics of Materials KW - General Materials Science SN - 1059-9495 TI - Correlation between Taylor Model Prediction and Transmission Electron Microscopy-Based Microstructural Investigations of Quasi-In Situ Tensile Deformation of Additively Manufactured FeCo Alloy VL - 30 ER - TY - JOUR AB - The addition of Ag to amorphous carbon (a-C) films is highly effective in tailoring the tribo-mechanical properties and biocompatibility. For biomedical applications, Ag-containing a-C (a-C:Ag) represents a promising film material for improving the biofunctional surface properties of Ti-based alloys. In a sputtering process, a-C:Ag films, with Ag contents up to 7.5 at.%, were deposited with a chemically graded TixCy interlayer onto Ti6Al4V. The tribo-mechanical and biocompatible properties of a-C:Ag were evaluated. The influence of the Ag content on these properties was analyzed and compared to those of uncoated Ti6Al4V. Raman spectroscopy reveals that the amount of incorporated Ag does not induce significant structural changes in the disordered network, only a reduced number of vacancies and sp3-coordinated C bonds within the sp2-dominant a-C network is assigned to the films with high Ag concentration. With increasing Ag content, stresses, hardness, and elastic modulus decrease from (2.02 ± 0.07) to (1.15 ± 0.03) GPa, from (17.4 ± 1.5) to (13.4 ± 0.9) GPa, and from (171.8 ± 8.1) to (138.5 ± 5.8) GPa, respectively. In tribometer tests, the friction behavior against Al2O3 in lubricated condition with a simulated-body-fluid-based lubricant is not affected by the Ag concentration, but the Al2O3 counterpart wear is reduced for all a-C:Ag films compared to a-C. The friction against ultra-high-molecular-weight polyethylene (UHMWPE) decreases continuously with increasing Ag concentration and the counterpart wear is lower at higher Ag contents. Compared to a-C:Ag, Ti6Al4V demonstrates lower friction against UHMWPE and higher friction against Al2O3. The a-C:Ag films are not exposed to abrasion by Al2O3 or pronounced material transfer of UHMWPE. The hardness difference and chemical affinity between the friction partners are decisive for the tribological behavior of a-C:Ag. Compared to Ti6Al4V, the a-C:Ag films show antibacterial activity against Staphylococcus aureus, while the proliferation of osteoblast-like cells is reduced by Ag. AU - Tillmann, Wolfgang AU - Lopes Dias, Nelson Filipe AU - Franke, Carlo AU - Kokalj, David AU - Stangier, Dominic AU - Filor, Viviane AU - Mateus-Vargas, Rafael Hernán AU - Oltmanns, Hilke AU - Kietzmann, Manfred AU - Meißner, Jessica AU - Hein, Maxwell AU - Pramanik, Sudipta AU - Hoyer, Kay-Peter AU - Schaper, Mirko AU - Nienhaus, Alexander AU - Thomann, Carl Arne AU - Debus, Jörg ID - 24243 JF - Surface and Coatings Technology SN - 0257-8972 TI - Tribo-mechanical properties and biocompatibility of Ag-containing amorphous carbon films deposited onto Ti6Al4V ER - TY - JOUR AB - Aluminium steel clad materials have high potential for industrial applications. Their mechanical properties are governed by an intermetallic layer, which forms upon heat treatment at the Al-Fe interface. Transmission electron microscopy was employed to identify the phases present at the interface by selective area electron diffraction and energy dispersive spectroscopy. Three phases were identified: orthorhombic Al5Fe2, monoclinic Al13Fe4 and cubic Al19Fe4MnSi2. An effective interdiffusion coefficient dependent on concentration was determined according to the Boltzmann–Matano method. The highest value of the interdiffusion coefficient was reached at the composition of the intermetallic phases. Afterwards, the process of diffusion considering the evaluated interdiffusion coefficient was simulated using the finite element method. Results of the simulations revealed that growth of the intermetallic phases proceeds preferentially in the direction of aluminium. AU - Křivská, Barbora AU - Šlapáková, Michaela AU - Veselý, Jozef AU - Kihoulou, Martin AU - Fekete, Klaudia AU - Minárik, Peter AU - Králík, Rostislav AU - Grydin, Olexandr AU - Stolbchenko, Mykhailo AU - Schaper, Mirko ID - 29815 IS - 24 JF - Materials KW - General Materials Science SN - 1996-1944 TI - Intermetallic Phases Identification and Diffusion Simulation in Twin-Roll Cast Al-Fe Clad Sheet VL - 14 ER - TY - JOUR AB - Laser beam melting (LBM) is an advanced manufacturing technology providing special features and the possibility to produce complex and individual parts directly from a CAD model. TiAl6V4 is the most common used titanium alloy particularly in biomedical applications. TiAl6Nb7 shows promising improvements especially regarding biocompatible properties due to the substitution of the hazardous vanadium. This work focuses on the examination of laser beam melted TiAl6Nb7. For microstructural investigation scanning electron microscopy including energydispersive x-ray spectroscopy as well as electron backscatter diffraction are utilized. The laser beam melted related acicular microstructure as well as the corresponding mechanical properties, which are determined by hardness measurements and tensile tests, are investigated. The laser beam melted alloy meets, except of breaking elongation A, the mechanical demands like ultimate tensile strength Rm, yield strength Rp0.2, Vickers hardness HV of international standard ISO 5832-11. Next steps contain comparison between TiAl6Nb7 and TiAl6V4 in different conditions. Further investigations aim at improving mechanical properties of TiAl6Nb7 by heat treatments and assessment of their influence on the microstructure as well as examination regarding the corrosive behavior in human bodylike conditions. AU - Hein, Maxwell AU - Hoyer, Kay-Peter AU - Schaper, Mirko ID - 24086 JF - Materialwissenschaft und Werkstofftechnik KW - Laser beam melting KW - titanium alloy KW - TiAl6Nb7 KW - biomedical engineering KW - implants SN - 0933-5137 TI - Additively processed TiAl6Nb7 alloy for biomedical applications VL - 52 ER - TY - JOUR AU - Cieslar, Miroslav AU - Králík, Rostislav AU - Bajtošová, Lucia AU - Křivská, Barbora AU - Hájek, Michal AU - Belejová, Sára AU - Grydin, Olexandr AU - Stolbchenko, Mykhailo AU - Schaper, Mirko ID - 29813 IS - S2 JF - Microscopy and Microanalysis KW - Instrumentation SN - 1431-9276 TI - High Temperature Annealing of Twin-Roll Cast Al-Li-Based Alloy Studied by In-situ SEM and STEM VL - 27 ER - TY - JOUR AU - Krüger, Jan Tobias AU - Hoyer, Kay-Peter AU - Filor, Viviane AU - Pramanik, Sudipta AU - Kietzmann, Manfred AU - Meißner, Jessica AU - Schaper, Mirko ID - 41514 JF - Journal of Alloys and Compounds KW - Materials Chemistry KW - Metals and Alloys KW - Mechanical Engineering KW - Mechanics of Materials SN - 0925-8388 TI - Novel AgCa and AgCaLa alloys for Fe-based bioresorbable implants with adapted degradation VL - 871 ER - TY - JOUR AU - Křivská, Barbora AU - Šlapáková, Michaela AU - Minárik, Peter AU - Fekete, Klaudia AU - Králík, Rostislav AU - Stolbchenko, Mykhailo AU - Schaper, Mirko AU - Grydin, Olexandr ID - 29814 IS - S2 JF - Microscopy and Microanalysis KW - Instrumentation SN - 1431-9276 TI - Intermetallic Phase Growth in Al-steel Clad Strip during In-situ Heating in TEM VL - 27 ER - TY - JOUR AU - Pramanik, Sudipta AU - Tasche, Lennart AU - Hoyer, Kay-Peter AU - Schaper, Mirko ID - 41515 JF - Additive Manufacturing KW - Industrial and Manufacturing Engineering KW - Engineering (miscellaneous) KW - General Materials Science KW - Biomedical Engineering SN - 2214-8604 TI - Investigating the microstructure of an additively manufactured FeCo alloy: an electron microscopy study VL - 46 ER - TY - JOUR AU - Camberg, Alan Adam AU - Andreiev, Anatolii AU - Pramanik, Sudipta AU - Hoyer, Kay-Peter AU - Tröster, Thomas AU - Schaper, Mirko ID - 27700 JF - Materials Science and Engineering: A SN - 0921-5093 TI - Strength enhancement of AlMg sheet metal parts by rapid heating and subsequent cold die stamping of severely cold-rolled blanks ER - TY - JOUR AB - AbstractWithin this research, the multiscale microstructural evolution before and after the tensile test of a FeCo alloy is addressed. X-ray µ-computer tomography (CT), electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM) are employed to determine the microstructure on different length scales. Microstructural evolution is studied by performing EBSD of the same area before and after the tensile test. As a result, $$\langle$$ 001$$\rangle$$ ||TD, $$\langle$$ 011$$\rangle$$ ||TD are hard orientations and $$\langle$$ 111$$\rangle$$ ||TD is soft orientations for deformation accommodation. It is not possible to predict the deformation of a single grain with the Taylor model. However, the Taylor model accurately predicts the orientation of all grains after deformation. {123}$$\langle$$ 111$$\rangle$$ is the most active slip system, and {112}$$\langle$$ 111$$\rangle$$ is the least active slip system. Both EBSD micrographs show grain subdivision after tensile testing. TEM images show the formation of dislocation cells. Correlative HRTEM images show unresolved lattice fringes at dislocation cell boundaries, whereas resolved lattice fringes are observed at dislocation cell interior. Since Schmid’s law is unable to predict the deformation behavior of grains, the boundary slip transmission accurately predicts the grain deformation behavior. AU - Pramanik, Sudipta AU - Tasche, Lennart AU - Hoyer, Kay-Peter AU - Schaper, Mirko ID - 24090 JF - Journal of Materials Engineering and Performance SN - 1059-9495 TI - Correlation between Taylor Model Prediction and Transmission Electron Microscopy-Based Microstructural Investigations of Quasi-In Situ Tensile Deformation of Additively Manufactured FeCo Alloy ER - TY - JOUR AB - Purpose The currently existing restrictions regarding the deployment of additively manufactured components because of poor surface roughness, porosity and residual stresses as well as their influence on the low-cycle fatigue (LCF) strength are addressed in this paper. Design/methodology/approach This study aims to evaluating the effect of different pre- and post-treatments on the LCF strength of additively manufactured 316L parts. Therefore, 316L specimens manufactured by laser powder bed fusion were examined in their as-built state as well as after grinding, or coating with regard to the surface roughness, residual stresses and LCF strength. To differentiate between topographical effects and residual stress-related phenomena, stress-relieved 316L specimens served as a reference throughout the investigations. To enable an alumina coating of the 316L components, atmospheric plasma spraying was used, and the near-surface residual stresses and the surface roughness are measured and investigated. Findings The results have shown that the applied pre- and post-treatments such as stress-relief heat treatment, grinding and alumina coating have each led to an increase in LCF strength of the 316L specimens. In contrast, the non-heat-treated specimens predominantly exhibited coating delamination. Originality/value To the best of the authors’ knowledge, this is the first study of the correlation between the LCF behavior of additively manufactured uncoated 316L specimens in comparison with additively manufactured 316L specimens with an alumina coating. AU - Garthe, Kai-Uwe AU - Hoyer, Kay-Peter AU - Hagen, Leif AU - Tillmann, Wolfgang AU - Schaper, Mirko ID - 27509 JF - Rapid Prototyping Journal SN - 1355-2546 TI - Correlation between pre- and post-treatments of additively manufactured 316L parts and the resulting low cycle fatigue behavior ER - TY - JOUR AB - Resorbable implants are highly beneficial to reduce patient burden since they need not be removed after a defined period. Currently, magnesium (Mg) and polymers are being applied as bioresorbable materials. However, for some applications the insufficient mechanical properties and high degradation rate of Mg cause the need for new materials. Iron (Fe)-based alloys are promising due to their biocompatibility and good mechanical properties, but their degradation rate is too low and needs to be adapted eg. via alloying with manganese (Mn). Besides, phases with high electrochemical potential lead to increased degradation of residual material with lower potential based on the galvanic coupling. Here, silver (Ag) is promising for the formation of such phases due to its high electrochemical potential (+0.8 V vs. SHE), immiscibility with Fe, biocompatibility, and anti-bacterial properties. Since remaining silver particles can lead to adverse consequences as thrombosis, these particles need to dissolve after the matrix material. Thus a silver alloy with high electrochemical potential, biocompatibility, and adjusted degradation behavior is required as an additive for iron-based bioresorbable materials. Several silver alloying systems are possible, but regarding the electrochemical potential and degradation behavior of binary alloys, calcium (Ca) and lanthanum (La) are best-suited considering their biocompatibility. Accordingly, this research addresses AgCa and AgCaLa alloys as additives for iron-based degradable materials with adapted degradation behavior. AU - Krüger, Jan Tobias AU - Hoyer, Kay-Peter AU - Filor, Viviane AU - Pramanik, Sudipta AU - Kietzmann, Manfred AU - Meißner, Jessica AU - Schaper, Mirko ID - 24087 JF - Journal of Alloys and Compounds SN - 0925-8388 TI - Novel AgCa and AgCaLa alloys for Fe-based bioresorbable implants with adapted degradation ER - TY - JOUR AB - Implementing the concept of mixed construction in modern automotive engineering requires the joining of sheet metal or extruded profiles with cast components made from different materials. As weight reduction is desired, these cast components are usually made from high-strength aluminium alloys of the Al-Si (Mn, Mg) system, which have limited weldability. The mechanical joinability of the cast components depends on their ductility, which is influenced by the microstructure. High-strength cast aluminium alloys have relatively low ductility, which leads to cracking of the joints. This limits the range of applications for cast aluminium alloys. In this study, an aluminium alloy of the Al-Si system AlSi9 is used to investigate relationships between solidification conditions during the sand casting process, microstructure, mechanical properties, and joinability. The demonstrator is a stepped plate with a minimum thickness of 2.0 mm and a maximum thickness of 4.0 mm, whereas the thickness difference between neighbour steps amounts to 0.5 mm. During casting trials, the solidification rates for different plate steps were measured. The microscopic investigations reveal a correlation between solidification rates and microstructure parameters such as secondary dendrite arm spacing. Furthermore, mechanical properties and the mechanical joinability are investigated. AU - Neuser, Moritz AU - Grydin, Olexandr AU - Andreiev, Anatolii AU - Schaper, Mirko ID - 23913 JF - Metals SN - 2075-4701 TI - Effect of Solidification Rates at Sand Casting on the Mechanical Joinability of a Cast Aluminium Alloy ER - TY - JOUR AB - AbstractLaser surface treatment of metals is one option to improve their properties for adhesive bonding. In this paper, a pulsed YVO4 Laser source with a wavelength of 1064 nm and a maximum power of 25 W was utilized to increase the surface area of the steel HCT490X in order to improve its bonding properties with a carbon fibre reinforced polymer (CFRP). Investigated was the influence of the scanning speed of the laser source on the bonding properties. For this purpose, the steel surfaces were ablated at a scanning speed between 1500 and 4500 mm/s. Afterwards the components were bonded with the adhesive HexBond™ 677. After lap shear tests were carried out on the specimen, the surfaces were inspected using scanning electron microscopy (SEM). The experiments revealed that the bonding quality can be improved with a high scanning speed, even when the surface is not completely ablated. AU - Voswinkel, Dietrich AU - Kloidt, D. AU - Grydin, Olexandr AU - Schaper, Mirko ID - 24565 IS - 2 JF - Production Engineering SN - 0944-6524 TI - Time efficient laser modification of steel surfaces for advanced bonding in hybrid materials VL - 15 ER - TY - JOUR AU - Engelkemeier, Katja AU - Sun, Aijia AU - Voswinkel, Dietrich AU - Grydin, Olexandr AU - Schaper, Mirko AU - Bremser, Wolfgang ID - 24566 JF - ChemElectroChem SN - 2196-0216 TI - Zinc Anodizing: Structural Diversity of Anodic Zinc Oxide Controlled by the Type of Electrolyte ER - TY - JOUR AU - Andreiev, Anatolii AU - Hoyer, Kay-Peter AU - Dula, Dimitri AU - Hengsbach, Florian AU - Grydin, Olexandr AU - Frolov, Yaroslav AU - Schaper, Mirko ID - 23897 JF - Materials Science and Engineering: A SN - 0921-5093 TI - Laser beam melting of functionally graded materials with application-adapted tailoring of magnetic and mechanical performance ER - TY - JOUR AU - Pramanik, Sudipta AU - Andreiev, Anatolii AU - Hoyer, Kay-Peter AU - Schaper, Mirko ID - 23911 JF - International Journal of Fatigue SN - 0142-1123 TI - Quasi in-situ analysis of fracture path during cyclic loading of double-edged U notched additively manufactured FeCo alloy ER - TY - JOUR AU - Pramanik, Sudipta AU - Tasche, Lennart AU - Hoyer, Kay-Peter AU - Schaper, Mirko ID - 24088 JF - Additive Manufacturing SN - 2214-8604 TI - Investigating the microstructure of an additively manufactured FeCo alloy: an electron microscopy study ER -