Improvement on mechanical properties and corrosion resistance of titanium-tantalum alloys in-situ fabricated via selective laser melting

In this study, the role of tantalum (Ta) on the phase transformation, microstructure evolution, mechanical properties and corrosion resistance of titanium-tantalum (Ti-Ta) alloys in-situ fabricated via selective laser melting (SLM) was investigated. Ti-Ta mixed powders with different Ta ratios ranging from 0 to 25 wt % were prepared by ball milling for the SLM process. With the increase of Ta content, the SLM-processed Ti-Ta alloys exhibits the microstructure evolution from the lath alpha grain to acicular alpha' + primary cellular beta grains, accompanying with the gradual suppression of martensite transformation. The beta-stabilized effect of Ta promotes the formation of beta(Ti, Ta) solid solution phase in the alloys. The rise of Ta addition in SLM-processed Ti-Ta alloys contributes to the improvement on the tensile strength from 641 to 1186 MPa and the microhardness from 257 to 353 HV, which results from a combined effect of grain refinement strengthening and the solid solution strengthening. The Young's modulus decreases from 115 to 89 GPa due to the increasing amount of beta phase. Additionally, the corrosion resistance of the Ti-Ta alloys is enhanced with few pits on the surfaces due to the increasing amount of Ta2O5 identified through X-ray photoelectron spectroscopy. These findings provide the knowledge and boost the further understanding on the SLM-processed Ti-Ta alloys as promising candidates for biomedical application. (C) 2019 Elsevier B.V. All rights reserved.