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. Graphic Abstract: [Figure not available: see fulltext.].