@article{33340, author = {{Hein, Maxwell and Lopes Dias, Nelson Filipe and Pramanik, Sudipta and Stangier, Dominic and Hoyer, Kay-Peter and Tillmann, Wolfgang and Schaper, Mirko}}, journal = {{Materials}}, title = {{{Heat Treatments of Metastable β Titanium Alloy Ti-24Nb-4Zr-8Sn Processed by Laser Powder Bed Fusion}}}, year = {{2022}}, } @article{36332, abstract = {{AlSi casting alloys combine excellent castability with high strength. Hence, this group of alloys is often used in the automotive sector. The challenge for this application is the brittle character of these alloys which leads to cracks during joint formation when mechanical joining technologies are used. A rise in ductility can be achieved by a considerable increase in the solidification rate which results in grain refinement. High solidification rates can be realized in twin–roll casting (TRC) by water-cooled rolls. Therefore, a hypoeutectic EN AC–AlSi9 (for European Norm - aluminum cast product) is manufactured by the TRC process and analyzed. Subsequently, joining investigations are performed on castings in as-cast and heat-treated condition using the self-piercing riveting process considering the joint formation and the load-bearing capacity. Due to the fine microstructure, the crack initiation can be avoided during joining, while maintaining the joining parameters, especially by specimens in heat treatment conditions. Furthermore, due to the extremely fine microstructure, the load-bearing capacity of the joint can be significantly increased in terms of the maximum load-bearing force and the energy absorbed.}}, author = {{Neuser, Moritz and Kappe, Fabian and Ostermeier, Jakob and Krüger, Jan Tobias and Bobbert, Mathias and Meschut, Gerson and Schaper, Mirko and Grydin, Olexandr}}, issn = {{1438-1656}}, journal = {{Advanced Engineering Materials}}, keywords = {{Condensed Matter Physics, General Materials Science}}, number = {{10}}, publisher = {{Wiley}}, title = {{{Mechanical Properties and Joinability of AlSi9 Alloy Manufactured by Twin‐Roll Casting}}}, doi = {{10.1002/adem.202200874}}, volume = {{24}}, year = {{2022}}, } @inbook{29771, author = {{Grydin, Olexandr and Mortensen, Dag and Neuser, Moritz and Lindholm, Dag and Fjaer, Hallvard G. and Schaper, Mirko}}, booktitle = {{Light Metals 2022}}, isbn = {{9783030925284}}, issn = {{2367-1181}}, publisher = {{Springer International Publishing}}, title = {{{Numerical and Experimental Investigation of Heat Transfer in the Solidification-Deformation Zone During Twin-Roll Casting of Aluminum Strips}}}, doi = {{10.1007/978-3-030-92529-1_96}}, year = {{2022}}, } @inproceedings{25047, author = {{Křivská, B and Šlapáková, M and Králík, R and Bajtošová, L and Cieslar, M and Grydin, Olexandr and Stolbchenko, M and Schaper, Mirko}}, booktitle = {{IOP Conference Series: Materials Science and Engineering}}, issn = {{1757-899X}}, title = {{{Resistivity and Formation of Intermetallic Layer in Aluminum-Steel Clad Strip}}}, doi = {{10.1088/1757-899x/1178/1/012035}}, volume = {{1178}}, year = {{2021}}, } @inproceedings{28440, author = {{Triebus, Marcel and Reitz, Alexander and Grydin, Olexandr and Grenz, Julian and Schneidt, Andreas and Erhardt, Rüdiger and Tröster, Thomas and Schaper, Mirko}}, booktitle = {{13th European LS-DYNA Conference 2021}}, location = {{Ulm}}, title = {{{Forming Simulation of Tailored Press Hardened Parts}}}, year = {{2021}}, } @article{26191, author = {{Voswinkel, Dietrich and Sapli, Hüseyin and Kloidt, Dennis and Heggemann, Thomas and Homberg, Werner and Grydin, Olexandr and Schaper, Mirko}}, issn = {{1757-8981}}, journal = {{IOP Conference Series: Materials Science and Engineering}}, title = {{{Improving the Accuracy of Deep Drawn Fiber-Metal Laminate Parts by Preliminary Surface Treatment}}}, doi = {{10.1088/1757-899x/1190/1/012028}}, year = {{2021}}, } @inproceedings{29812, abstract = {{Aluminum-steel clad composites are used as structural elements in car bodies and chases as well as in the chemical industry due to a combination of high strength of steel, low density of Al and high corrosion resistance of both materials. An important parameter influencing mechanical properties of the composite is the microstructure of the bonding region between Al and steel layer. During manufacturing of the final product, clad sheets can be subjected to elevated temperatures which enhance diffusion between the metals. As a result, a brittle intermetallic phase, deteriorating the bond strength between steel and aluminum, forms at the interface. This paper focuses on study of the interfacial microstructure in a twin-roll cast Al-steel clad strip and its evolution during in-situ annealing in transmission electron microscope. Due to isochronal annealing above 500 °C, Al5Fe2 phase forms at the interface. Nucleation centers formed at the beginning of heating experiment expand and form continuous layer. The kinetics of the growth follows the parabolic law typical for diffusion-controlled phase transformations.}}, author = {{Křivská, Barbora and Šlapáková, Michaela and Minárik, Peter and Fekete, Klaudia and Králík, Rostislav and Stolbchenko, Mykhailo and Schaper, Mirko and Grydin, Olexandr}}, booktitle = {{APPLIED PHYSICS OF CONDENSED MATTER (APCOM 2021)}}, issn = {{0094-243X}}, location = {{Online}}, publisher = {{AIP Publishing}}, title = {{{In-situ TEM observation of intermetallic phase growth in Al-steel clad sheet}}}, doi = {{10.1063/5.0067491}}, year = {{2021}}, } @article{24535, abstract = {{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.}}, author = {{Neuser, Moritz and Grydin, Olexandr and Andreiev, Anatolii and Schaper, Mirko}}, issn = {{2075-4701}}, journal = {{Metals}}, title = {{{Effect of Solidification Rates at Sand Casting on the Mechanical Joinability of a Cast Aluminium Alloy}}}, doi = {{10.3390/met11081304}}, year = {{2021}}, } @article{24537, author = {{Neuser, Moritz and Kappe, Fabian and Busch, M and Grydin, Olexandr and Bobbert, Mathias and Schaper, Mirko and Meschut, Gerson and Hausotte, T}}, issn = {{1757-8981}}, journal = {{IOP Conference Series: Materials Science and Engineering}}, title = {{{Joining suitability of cast aluminium for self-piercing riveting}}}, doi = {{10.1088/1757-899x/1157/1/012005}}, year = {{2021}}, } @article{29089, author = {{Westermann, Hendrik and Reitz, Alexander and Mahnken, Rolf and Grydin, Olexandr and Schaper, Mirko}}, issn = {{1617-7061}}, journal = {{PAMM}}, title = {{{Constitutive modeling of viscoplasticity including phase transformations for graded thermo‐mechanical processing}}}, doi = {{10.1002/pamm.202100041}}, year = {{2021}}, } @article{41511, author = {{Hein, Maxwell and Hoyer, Kay-Peter and Schaper, Mirko}}, issn = {{0933-5137}}, journal = {{Materialwissenschaft und Werkstofftechnik}}, keywords = {{Mechanical Engineering, Mechanics of Materials, Condensed Matter Physics, General Materials Science}}, number = {{7}}, pages = {{703--716}}, publisher = {{Wiley}}, title = {{{Additively processed TiAl6Nb7 alloy for biomedical applications}}}, doi = {{10.1002/mawe.202000288}}, volume = {{52}}, year = {{2021}}, } @article{41507, abstract = {{ 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. }}, author = {{Garthe, Kai-Uwe and Hoyer, Kay-Peter and Hagen, Leif and Tillmann, Wolfgang and Schaper, Mirko}}, issn = {{1355-2546}}, journal = {{Rapid Prototyping Journal}}, keywords = {{Industrial and Manufacturing Engineering, Mechanical Engineering}}, number = {{5}}, pages = {{833--840}}, publisher = {{Emerald}}, title = {{{Correlation between pre- and post-treatments of additively manufactured 316L parts and the resulting low cycle fatigue behavior}}}, doi = {{10.1108/rpj-01-2021-0017}}, volume = {{28}}, year = {{2021}}, } @article{41506, abstract = {{Processing aluminum alloys employing powder bed fusion of metals (PBF-LB/M) is becoming more attractive for the industry, especially if lightweight applications are needed. Unfortunately, high-strength aluminum alloys such as AA7075 are prone to hot cracking during PBF-LB/M, as well as welding. Both a large solidification range promoted by the alloying elements zinc and copper and a high thermal gradient accompanied with the manufacturing process conditions lead to or favor hot cracking. In the present study, a simple method for modifying the powder surface with titanium carbide nanoparticles (NPs) as a nucleating agent is aimed. The effect on the microstructure with different amounts of the nucleating agent is shown. For the aluminum alloy 7075 with 2.5 ma% titanium carbide nanoparticles, manufactured via PBF-LB/M, crack-free samples with a refined microstructure having no discernible melt pool boundaries and columnar grains are observed. After using a two-step ageing heat treatment, ultimate tensile strengths up to 465 MPa and an 8.9% elongation at break are achieved. Furthermore, it is demonstrated that not all nanoparticles used remain in the melt pool during PBF-LB/M.}}, author = {{Heiland, Steffen and Milkereit, Benjamin and Hoyer, Kay-Peter and Zhuravlev, Evgeny and Kessler, Olaf and Schaper, Mirko}}, issn = {{1996-1944}}, journal = {{Materials}}, keywords = {{General Materials Science}}, number = {{23}}, publisher = {{MDPI AG}}, title = {{{Requirements for Processing High-Strength AlZnMgCu Alloys with PBF-LB/M to Achieve Crack-Free and Dense Parts}}}, doi = {{10.3390/ma14237190}}, volume = {{14}}, year = {{2021}}, } @article{24790, abstract = {{Implants often overtake body function just for a certain time and remain as an unnecessary foreign body or have to be removed. Thus, resorbable implants are highly beneficial to reduce patient burden. Besides established materials, Iron-(Fe)-based alloys are in focus due to superior mechanical properties and good biocompatibility. However, their degradation rate needs to be increased. Phases with high electrochemical potential could promote the dissolution of residual material based on the galvanic coupling. Silver (Ag) is promising due to its high electrochemical potential (+0.8 V vs. SHE), immiscibility with Fe, biocompatibility, and anti-bacterial properties. But to prevent adverse consequences the Ag-particles, remaining after dissolution of the matrix, need to dissolve. Thus, a bioresorbable Ag-alloy is required. Regarding the electrochemical potential and degradation behavior of binary alloys, Cerium (Ce) and Lanthanum (La) are well-suited considering their biocompatibility and antibacterial behavior. Accordingly, this research addresses AgCe and AgCeLa alloys as additives for Fe-based materials with adapted degradation behavior. Furthermore, degradable Ag-alloys combined with inert implant materials could enable the controlled release of antibacterial active Ag-ions.}}, author = {{Krüger, Jan Tobias and Hoyer, Kay-Peter and Schaper, Mirko}}, issn = {{0167-577X}}, journal = {{Materials Letters}}, title = {{{Bioresorbable AgCe and AgCeLa alloys for adapted Fe-based implants}}}, doi = {{10.1016/j.matlet.2021.130890}}, volume = {{306}}, year = {{2021}}, } @article{41516, author = {{Tillmann, Wolfgang and Lopes Dias, Nelson Filipe and Franke, Carlo and Kokalj, David and Stangier, Dominic and Filor, Viviane and Mateus-Vargas, Rafael Hernán and Oltmanns, Hilke and Kietzmann, Manfred and Meißner, Jessica and Hein, Maxwell and Pramanik, Sudipta and Hoyer, Kay-Peter and Schaper, Mirko and Nienhaus, Alexander and Thomann, Carl Arne and Debus, Jörg}}, issn = {{0257-8972}}, journal = {{Surface and Coatings Technology}}, keywords = {{Materials Chemistry, Surfaces, Coatings and Films, Surfaces and Interfaces, Condensed Matter Physics, General Chemistry}}, publisher = {{Elsevier BV}}, title = {{{Tribo-mechanical properties and biocompatibility of Ag-containing amorphous carbon films deposited onto Ti6Al4V}}}, doi = {{10.1016/j.surfcoat.2021.127384}}, volume = {{421}}, year = {{2021}}, } @article{41512, author = {{Andreiev, Anatolii and Hoyer, Kay-Peter and Dula, Dimitri and Hengsbach, Florian and Grydin, Olexandr and Frolov, Yaroslav and Schaper, Mirko}}, issn = {{0921-5093}}, journal = {{Materials Science and Engineering: A}}, keywords = {{Mechanical Engineering, Mechanics of Materials, Condensed Matter Physics, General Materials Science}}, publisher = {{Elsevier BV}}, title = {{{Laser beam melting of functionally graded materials with application-adapted tailoring of magnetic and mechanical performance}}}, doi = {{10.1016/j.msea.2021.141662}}, volume = {{822}}, year = {{2021}}, } @article{41510, author = {{Pramanik, Sudipta and Andreiev, Anatolii and Hoyer, Kay-Peter and Schaper, Mirko}}, issn = {{0142-1123}}, journal = {{International Journal of Fatigue}}, keywords = {{Industrial and Manufacturing Engineering, Mechanical Engineering, Mechanics of Materials, General Materials Science, Modeling and Simulation}}, publisher = {{Elsevier BV}}, title = {{{Quasi in-situ analysis of fracture path during cyclic loading of double-edged U notched additively manufactured FeCo alloy}}}, doi = {{10.1016/j.ijfatigue.2021.106498}}, volume = {{153}}, year = {{2021}}, } @article{41509, author = {{Krüger, Jan Tobias and Hoyer, Kay-Peter and Schaper, Mirko}}, issn = {{0167-577X}}, journal = {{Materials Letters}}, keywords = {{Mechanical Engineering, Mechanics of Materials, Condensed Matter Physics, General Materials Science}}, publisher = {{Elsevier BV}}, title = {{{Bioresorbable AgCe and AgCeLa alloys for adapted Fe-based implants}}}, doi = {{10.1016/j.matlet.2021.130890}}, volume = {{306}}, year = {{2021}}, } @article{41517, abstract = {{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.}}, author = {{Pramanik, Sudipta and Tasche, Lennart and Hoyer, Kay-Peter and Schaper, Mirko}}, issn = {{1059-9495}}, journal = {{Journal of Materials Engineering and Performance}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, number = {{11}}, pages = {{8048--8056}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Correlation between Taylor Model Prediction and Transmission Electron Microscopy-Based Microstructural Investigations of Quasi-In Situ Tensile Deformation of Additively Manufactured FeCo Alloy}}}, doi = {{10.1007/s11665-021-06065-9}}, volume = {{30}}, year = {{2021}}, } @article{24243, abstract = {{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.}}, author = {{Tillmann, Wolfgang and Lopes Dias, Nelson Filipe and Franke, Carlo and Kokalj, David and Stangier, Dominic and Filor, Viviane and Mateus-Vargas, Rafael Hernán and Oltmanns, Hilke and Kietzmann, Manfred and Meißner, Jessica and Hein, Maxwell and Pramanik, Sudipta and Hoyer, Kay-Peter and Schaper, Mirko and Nienhaus, Alexander and Thomann, Carl Arne and Debus, Jörg}}, issn = {{0257-8972}}, journal = {{Surface and Coatings Technology}}, title = {{{Tribo-mechanical properties and biocompatibility of Ag-containing amorphous carbon films deposited onto Ti6Al4V}}}, doi = {{10.1016/j.surfcoat.2021.127384}}, year = {{2021}}, }