Corrosion and tribocorrosion behavior of equiatomic refractory medium entropy TiZr(Hf, Ta, Nb) alloys in chloride solutions

Equiatomic TiZr(Hf, Ta, Nb) medium entropy alloys (MEAs) were developed to achieve higher corrosion resistance than pure Ti. Nb and Ta alloying can greatly improve the corrosion resistance of Ti-50Zr (at%) alloys by reducing point defects in passive films. The oxide thickness for elements in passive films on TiZr(Hf, Ta, Nb) alloys increase significantly, following Hf > Zr > Ti > Nb > Ta, which was determined by the ability of elements to form oxides. Serious ploughing and delamination wear result in a higher tribocorrosion rate for TiZrNb alloy. The wear mechanisms for the three MEAs was discussed.