Muti-mechanism of the improving wear performance for titanium alloy via laser powder bed fusion

Abstract

Wear is the key issue hindering the further application of titanium alloy. The aim of this work was to explore the strengthening mechanisms for the wear properties of Ti–15Mo alloys via laser powder bed fusion (LPBF) by the La2O3 addition. The results showed that the grain of LPBF-fabricated Ti–15Mo/La2O3 composites was obviously refined after La2O3 addition by heterogeneous nucleation and inhibited grain growth. The average grain size of Ti–15Mo/(0.2 wt%, 0.4 wt%, 0.6 wt% and 0.8 wt%) La2O3 composites is 11.75 μm, 10.85 μm, 10.39 μm, and 9.99 μm, respectively. The wear rate of Ti–15Mo/(0.2 wt% - 0.8 wt%) La2O3 composites is 1.5916 × 10−4mm3N−1m−1, 1.2885 × 10−4mm3N−1m−1, 0.6821 × 10−4mm3N−1m−1 and 0.6063 × 10−4mm3N−1m−1, respectively. Thanks to the combined effect of fine grain strengthening, grain boundary strengthening, precipitation strengthening, dispersion strengthening and dislocation strengthening, the wear resistance of the obtained sample exceeds that of the LPBF-fabricated Ti–15Mo sample more than five times and that of the LPBF-fabricated CP-Ti sample more than ten times.