Effect of interstitial oxygen /nitrogen on mechanical and wear properties of TiZrHfNb refractory high-entropy alloy

Abstract

Refractory high-entropy alloy (RHEA), as a kind of promising alloy, has received particular attention in high-temperature applications because of its stability and excellent high-temperature softening resistance. However, most RHEAs are in the strength-ductility trade-off dilemma, which leads to limited applications. In this study, the TiZrHfNb alloy with better ductility is selected as the base alloy, and the strength of the alloy is enhanced by interstitial solid-solution strengthening of O and N atoms, thereby improving the wear resistance of the alloy. All alloys exhibit a body-centered cubic (BCC) structure. The O-doped alloy exhibits a remarkable balance between strength and ductility, while the N-doped alloy displays the highest levels of hardness and yield strength, attributed to the grain boundary strengthening and solid-solution strengthening effects of interstitial atoms. The N-doped alloy has the lowest wear rate at room temperature and 500 ℃, which is attributed to the hardening effect of N atoms. At 25 ℃, the main wear mechanisms are severe abrasive wear, adhesive wear, and oxidative wear. At 500 ℃, the dominant wear mechanisms change to oxidative wear and slight abrasive wear. The oxide layer on the worn surface can decrease the coefficient of friction (COF) and improve the wear resistance.