In situ production of low-modulus Ti–Nb alloys by selective laser melting and their functional assessment toward orthopedic applications

Abstract

This work aimed to manufacture Ti–28.5Nb and Ti–40.0Nb (wt%) alloys in situ via selective laser melting (SLM) from Ti and Nb elemental powders. X-ray diffraction analysis revealed complete β-phase (cubic) in Ti–40.0Nb and a mixture of (α′′ orthorhombic + β cubic) phases in Ti–28.5Nb were formed, whereas few of the Nb particles remained only partially fused during manufacturing. The fraction of partially melted Nb particles was determined as ∼2 and ∼18% in Ti–28.5Nb and Ti–40Nb, respectively. Mechanical characterization revealed higher hardness and more strength in Ti–28.5Nb than in Ti–40.0Nb due to the presence of the α′′ phase in the former. Tribocorrosion tests reveal a significantly better wear-corrosion resistance for Ti–40.0Nb, as determined from a lower total volume loss in Ti–40.0Nb (∼2 × 10⁻⁴ mm⁻³) than in Ti–28.5Nb (∼13 × 10⁻² mm⁻³). The lower volume loss and better corrosion resistance behavior are attributed to the β phase, which was dominant in Ti–40.0Nb. Cell studies reveal no toxicity for up to 7 days. Both the alloys were better at supporting cell proliferation than wrought Ti6Al4V. This study presents a route to preparing Ti–Nb alloys in situ by SLM that are promising candidates for biomedical applications.