Effect of sintering temperature on phase formation, hardness, and wear behavior of TiMoVWCr refractory high-entropy alloy

In this study, TiMoVWCr high-entropy refractory alloy was prepared mechanical alloying (MA) and spark plasma sintering (SPS) using an equiatomic elemental composition. Phase evolution during MA revealed the formation of a single-phase BCC solid solution after 20 h of milling, attributed to severe plastic deformation and enhanced atomic diffusion. Increasing the milling time resulted in finer particle size during the mechanical alloying process. After the SPS process at different temperatures, the final structure had BCC1, BCC2, and Cr-rich phases. As the temperature increased, the intensity of the BCC1 and Cr-rich phases decreased due to phase redistribution and at 1800 °C, the BCC2 phase became dominant, indicating its thermodynamic stability under high-temperature conditions. The hardness of the samples at temperatures of 1200, 1400, 1600 and 1800 °C was 257, 493, 833 and 1206 HV, respectively. This increase in hardness with increasing temperature is attributed to phase transformation, solid solution strengthening, microstructural densification and structural homogeneity. Concurrently, the wear rate decreased from 41.7 × 10 −4 mm 3 /N.m for the sample sintered at 1200 °C to 3.95 × 10 −4 mm 3 /N.m for the sample sintered at 1800 °C, which was the result of increased hardness and improved load-bearing capacity due to the formation of a homogeneous BCC2 phase. In addition, the wear mechanism changed from abrasive and adhesive wear to oxidation wear with increasing temperature. These properties indicate the high capability of this alloy for use in high temperature and abrasive environments.