A high strength and low modulus metastable β Ti-12Mo-6Zr-2Fe alloy fabricated by laser powder bed fusion in-situ alloying

Research output: Contribution to journalArticlepeer-review

Authors

  • Ranxi Duan
  • Weiwei Zhu
  • Fuzeng Ren

Colleges, School and Institutes

External organisations

  • South University of Science and Technology of China

Abstract

Biocompatible β Ti-alloys with high strength and low modulus are of interest for additive manufacturing of biomedical implants. In this study, a metastable β Ti-12Mo-6Zr-2Fe (TMZF) alloy with highly dense structure was successfully fabricated by laser powder bed fusion (LPBF) from low-cost elemental powders. The applied different scanning strategies (simple and chess scan), and post heat treatment can regulate both the texture and secondary phases. The formation of strong {100}< 001 > texture leads to the low elastic modulus of TMZF alloys, while nano-sized α" phases induce significantly strengthening effect. The as-fabricated TMZF alloy via simple scanning strategy shows considerably high strength due to the high density of α", ω phases and sessile dislocations, but it is brittle owing to the presence of ω phase. The TMZF alloy, manufactured using chess scanning strategy, possessed high yield strength of 1,026 MPa, low modulus of 85.7 GPa and good ductility of 12.7%. This results from its unique hierarchical microstructure containing α" phases, heterogeneous grains and the formation of {100}< 001 > texture. After solution heat treatment, the specimens exhibit stronger {100} < 001 > texture, hence lower modulus of 70.9 GPa. High yield strength of 943 MPa was maintained due to the formation of plate-like α" precipitates. The TMZF alloy fabricated by in-situ alloying based LPBF demonstrates comparable strength to that of Ti-6Al-4V alloy, but much lower elastic modulus, suggesting that it could be a potential candidate for some implant applications.

Bibliographic note

Funding Information: This work was financially supported by the Fundamental Research Program of Shenzhen (Grant No. JCYJ20170412153039309 ), and Guangdong Innovative & Entrepreneurial Research Team Program, China (No. 2016ZT06C279 ). The authors acknowledge the assistance of SUSTech Core Research Facilities which receive support from Presidential fund and Development and Reform Commission of Shenzhen Municipality, China. B. Cai thanks the support from the Royal Society International Exchange, United Kingdom Grant ( IEC\NSFC\191319 ). We also thank Dr. Minshi Wang at UoB for the HAADF-TEM characterisation, and Prof. Zuming Liu and Mr. Bing Wei at Central South University for the EPMA characterisation. Publisher Copyright: © 2020 Elsevier B.V. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

Details

Original languageEnglish
Article number101708
JournalAdditive Manufacturing
Publication statusAccepted/In press - 2020

Keywords

  • In-situ alloying, Laser powder bed fusion, Mechanical properties, Phase transformation, β-titanium alloys