Outstanding Mild Wear Performance of Ti–29Nb–14Ta–4.5Zr Alloy Through Subsurface Grain Refinement and Supporting Effect of Transformation Induced Plasticity

Abstract

The tribological performance of Ti–29Nb–14Ta–4.5Zr alloy against Ti–6Al–4V ELI was investigated for the mild condition, emphasized on the superficial changes and changes underneath the wear track. The results of X-ray photoelectron spectroscopy indicated that TiO2, Nb2O, Ta2O and Zr2O oxides aggregated to form a protective tribo-layer, which effectively prevented further superficial damages. Development of fine-grain layer and the occurrence of phase transformation of β → α’’/ω were characterized as the main wear-induced evolution of the subsurface layer. The wear-induced transformation increases the hardenability of the subsurface layer, effectively support the worn surface and prevent premature cracking. These phenomenal evolutions were led to a simultaneous increase in the strength and ductility and subsequently wear loss reduction in comparison to the Ti64 ELI.