Review — Research and Development of Titanium-Containing Biomedical High Entropy Alloys (BioHEAs) Utilizing Rapid Solidification via Laser-Powder Bed Fusion

Abstract

High entropy alloys (HEAs) have been developed as a new class of structural materials that consist of multicomponent elements with an approximately equiatomic ratio for increasing the mixing entropy to stabilize the solid solution phase. HEA for biomedical applications (BioHEA) was first developed in Japan; HEA comprising nonbiotoxic elements was specifically designed, demonstrating excellent mechanical properties and biocompatibility. However, elemental segregation, often observed in BioHEAs, hinders the inherent functions derived from high entropy effects and solid solution hardening. In this review article, elemental homogenization and functionalization of BioHEAs utilized by ultrarapid cooling via laser-powder bed fusion and the characteristics of these BioHEAs, especially focusing on their excellent properties for biomedical applications, are introduced.

Effect of Cooling Rate on Powder Characteristics and Microstructural Evolution of Gas Atomized β-Solidifying γ-TiAl Alloy Powder

“…Lastly, among the various manufacturing methodologies, the AM process promises almost the same microstructural features demonstrated in this study because of the ultra-high cooling rate temperature fields and their repetitive thermal history during the process. 35) Therefore, the investigated microstructural evolution features in this study may have the potential to contribute to the understanding of microstructure characteristics in additively fabricated γ-TiAl alloys.…”