Microstructure and Mechanical Behavior of Ti–25Nb–25Zr Alloy Prepared from Pre-Alloyed and Hydride-Mixed Elemental Powders

Abstract

A study has been undertaken on the feasibility of the powder-metallurgy manufacturing process to fabricate ¢-type Ti25Nb25Zr alloy (mass%) for biomedical applications. The Ti25Nb25Zr alloy was fabricated from a mixture of TiH 2 with constituent elemental powders, and from a pre-alloyed Plasma Rotating Electrode Processed (PREP) Ti25Nb25Zr powder, separately. It is shown that different processing methods led to different microstructures and mechanical properties. The Ti25Nb25Zr compact prepared by pre-alloyed powder exhibits poor strength whereas TiH 2 processed Ti25Nb25Zr compact exhibits comparatively ultra-fine grained microstructure with significantly improved strength. The proposed fabrication method may have several opportunities to fabricate metallic alloys with enhanced mechanical properties.

Recent Progress in Our Understanding of Phase Stability, Atomic Structures and Mechanical and Functional Properties of High-Entropy Alloys

“…This is also the case for highentropy alloys for better balanced mechanical properties. Therefore, may recent studies have focused on alloy design 12,9194) including atomic (defect) structure and phase stability, 95108) processing, 11,109119) characterization of resultant microstructures 120127) and mechanical properties, 13,14,128138) and modelling of resultant microstructures 139142) and mechanical properties, 16,143147) pursuing the achievement of better-balanced mechanical properties. Indeed, some excellent examples can be found for achieving fabulous balanced mechanical properties through utilizing TRIP (transformation-induced plasticity) and TWIP (twinning-induced plasticity) effects by tuning SF energy, 148,149) through tuning heterogeneous (bimodal) microstructures 150,151) and through utilizing secondary/tertiary-phase precipitates.…”

“…4). The special issue includes 8 regular articles in total, covering studies on processing, 11) alloy design, 12) characterization of mechanical properties, 13,14) solidification microstructure, 15) and modelling of mechanical properties, 16) energetics of lattice defects such as vacancies 17) and interstitials. 18) This special issue is intended to provide some preliminary outcomes of a national research project, Grantin Aid for Scientific Research on Innovative Areas 'High-Entropy Alloys: New Scientific Principle for Controlling Variety and Inhomogeneity of Elements', which has been launched in 2018 as a 5-year research project supported by Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan.…”