An investigation of Ti addition to optimize the tribological properties of TiCrNbTaW refractory high-entropy alloy

Abstract

Many refractory high-entropy alloys (RHEAs) with high melting points suffer from severe wear-fracture failures due to compositional segregation, which is a key factor limiting their widespread application as structural parts. In this work, two novel Ti_xCrNbTaW (x = 1 and 1.5) RHEAs were prepared using composition modulation and liquid phase assisted sintering strategies. The results showed that the further addition of Ti enhanced the strength, toughness and microstructural homogeneity of the RHEAs, which effectively suppressed the wear-fracture behavior. In addition, the dense oxidized amorphous layer formed in-situ has higher hardness than the matrix, which can provide additional load-bearing capacity. The synergistic effect of the above factors promotes the wear rate of Ti1.5 alloy to be as low as 2.9 × 10⁻⁵ mm³/(N·m). The present work provides some insights into the design of high anti-wear RHEAs.