Effect of heat-treatment time on microstructure and tribological behavior of (TiVCrAlMo)N high-entropy alloy films

Abstract

In this work, the effect of heat-treatment time (0 h, 2 h, 4 h, and 8 h) at 300 °C on the microstructure and tribological properties of (TiVCrAlMo)N high-entropy alloy (HEA) films are studied in detail. The results indicate that the HEA films with and without heat-treatment are all composed of a single FCC solid solution phase. With the increase of heat-treatment time, the lattice constant decreases gradually but the surface roughness has a tendency to increase, however, the microhardness and tribological properties don't show a linear relationship. The HEA film with 2 h heat-treatment has a relatively low micro-hardness, but the lowest friction coefficient (~0.22) with the best wear-resistance, while the HEA film with 8 h heat-treatment has the highest micro-hardness, but has the worst wear-resistance. The lowest friction coefficient of HEA film with 2 h heat-treatment is mainly due to the highest content of the MoO3 self-lubricating phase. Moreover, owing to the different micro-hardness and the different surface formation with different heat-treatment times, the wear mechanisms of these HEA films are quite different.