Development of TiNbTaZrMo bio-high entropy alloy (BioHEA) super-solid solution by selective laser melting, and its improved mechanical property and biocompatibility
Takuya Ishimoto, Ryosuke Ozasa, Kana Nakano, Markus Weinmann, C. Schnitter, Melanie Stenzel, Aira Matsugaki, Takeshi Nagase, Tadaaki Matsuzaka, Mitsuharu Todai, Hyoung Seop Kim, Takayoshi Nakano
Abstract
BioHEAs, specifically designed high entropy alloy (HEA) systems for biomedical applications, represent a new era for biometals. However, recent challenges are (1) the poor shape customizability, and (2) the inevitable severe segregation due to the intrinsic fact that HEA is an ultra-multicomponent alloy system. To achieve shape customization and suppression of elemental segregation simultaneously, we used an extremely high cooling rate (~107 K/s) of the selective laser melting (SLM) process. We, for the first time, developed pre-alloyed Ti1.4Nb0.6Ta0.6Zr1.4Mo0.6 BioHEA powders and SLM-built parts with low porosity, customizable shape, excellent yield stress, and good biocompatibility. The SLM-built specimens showed drastically suppressed elemental segregation compared to the cast counterpart, representing realization of a super-solid solution. As a result, the 0.2% proof stress reached 1690 ± 78 MPa, which is significantly higher than that of cast Ti1.4Nb0.6Ta0.6Zr1.4Mo0.6 (1140 MPa). The SLM-built Ti1.4Nb0.6Ta0.6Zr1.4Mo0.6 BioHEA is promising as a next-generation metallic material for biomedical applications.