Matthias Bönisch

Bio: Matthias Bönisch is an academic researcher from Dresden University of Technology. The author has contributed to research in topics: Microstructure & Alloy. The author has an hindex of 20, co-authored 26 publications receiving 1224 citations. Previous affiliations of Matthias Bönisch include University of Illinois at Urbana–Champaign & Leibniz Association.

Comparative study of microstructures and mechanical properties of in situ Ti–TiB composites produced by selective laser melting, powder metallurgy, and casting technologies

Abstract: This study presents results of selective laser melting (SLM), powder metallurgy (PM), and casting technologies applied for producing Ti–TiB composites from Ti–TiB2 powder. Diffraction patterns and microstructural investigations reveal that chemical reaction occurred between Ti and TiB2 during all the three processes, leading to the formation of Ti–TiB composites. The ultimate compressive strength of SLM-processed and cast samples are 1421 and 1434 MPa, respectively, whereas the ultimate compressive strengths of PM-processed 25%, 29%, and 36% porous samples are 510, 414, and 310 MPa, respectively. The Young’s moduli of porous composite samples are 70, 45, and 23 GPa for 25%, 29%, and 36% porosity levels, respectively, and are lower than those of SLM-processed (145 GPa) and cast (142 GPa) samples. Fracture analysis of the SLM-processed and cast samples shows shear fracture and microcracks across the samples, whereas failure of porous samples occurs due to porosities and weak bonds among particles.

Composition optimization of low modulus and high-strength TiNb-based alloys for biomedical applications

Abstract: The effect of chemical composition on microstructure and tensile properties of a series of low modulus Ti-Nb-Cu-Ni-Al alloys was studied. These alloys consist of primary micrometer-sized β-Ti dendrites surrounded by intermetallic phases. The morphology of the intermetallic phases is strongly affected by composition. Due to the composite microstructure, the alloys exhibit a low Young's modulus (77-84GPa) together with a high yield strength of about 1000MPa as well as moderate tensile ductility. The results demonstrate that complete substitution of Al by Ti reduces the Young's modulus by 5%. Increasing Nb content at the expense of Ti causes a significant improvement of tensile ductility.

Production of Porous β-Type Ti-40Nb Alloy for Biomedical Applications: Comparison of Selective Laser Melting and Hot Pressing.

Abstract: We used selective laser melting (SLM) and hot pressing of mechanically-alloyed β-type Ti-40Nb powder to fabricate macroporous bulk specimens (solid cylinders). The total porosity, compressive strength, and compressive elastic modulus of the SLM-fabricated material were determined as 17% ± 1%, 968 ± 8 MPa, and 33 ± 2 GPa, respectively. The alloy's elastic modulus is comparable to that of healthy cancellous bone. The comparable results for the hot-pressed material were 3% ± 2%, 1400 ± 19 MPa, and 77 ± 3 GPa. This difference in mechanical properties results from different porosity and phase composition of the two alloys. Both SLM-fabricated and hot-pressed cylinders demonstrated good in vitro biocompatibility. The presented results suggest that the SLM-fabricated alloy may be preferable to the hot-pressed alloy for biomedical applications, such as the manufacture of load-bearing metallic components for total joint replacements.

High-entropy alloys

Abstract: Alloying has long been used to confer desirable properties to materials. Typically, it involves the addition of relatively small amounts of secondary elements to a primary element. For the past decade and a half, however, a new alloying strategy that involves the combination of multiple principal elements in high concentrations to create new materials called high-entropy alloys has been in vogue. The multi-dimensional compositional space that can be tackled with this approach is practically limitless, and only tiny regions have been investigated so far. Nevertheless, a few high-entropy alloys have already been shown to possess exceptional properties, exceeding those of conventional alloys, and other outstanding high-entropy alloys are likely to be discovered in the future. Here, we review recent progress in understanding the salient features of high-entropy alloys. Model alloys whose behaviour has been carefully investigated are highlighted and their fundamental properties and underlying elementary mechanisms discussed. We also address the vast compositional space that remains to be explored and outline fruitful ways to identify regions within this space where high-entropy alloys with potentially interesting properties may be lurking. High-entropy alloys have greatly expanded the compositional space for alloy design. In this Review, the authors discuss model high-entropy alloys with interesting properties, the physical mechanisms responsible for their behaviour and fruitful ways to probe and discover new materials in the vast compositional space that remains to be explored.

New Developments of Ti-Based Alloys for Biomedical Applications

Abstract: Ti-based alloys are finding ever-increasing applications in biomaterials due to their excellent mechanical, physical and biological performance. Nowdays, low modulus β-type Ti-based alloys are still being developed. Meanwhile, porous Ti-based alloys are being developed as an alternative orthopedic implant material, as they can provide good biological fixation through bone tissue ingrowth into the porous network. This paper focuses on recent developments of biomedical Ti-based alloys. It can be divided into four main sections. The first section focuses on the fundamental requirements titanium biomaterial should fulfill and its market and application prospects. This section is followed by discussing basic phases, alloying elements and mechanical properties of low modulus β-type Ti-based alloys. Thermal treatment, grain size, texture and properties in Ti-based alloys and their limitations are dicussed in the third section. Finally, the fourth section reviews the influence of microstructural configurations on mechanical properties of porous Ti-based alloys and all known methods for fabricating porous Ti-based alloys. This section also reviews prospects and challenges of porous Ti-based alloys, emphasizing their current status, future opportunities and obstacles for expanded applications. Overall, efforts have been made to reveal the latest scenario of bulk and porous Ti-based materials for biomedical applications.