Structural and Comprehensive Performance of CoCrFeMnNi High-Entropy Alloys via Fast Hot-Pressed Sintering: Effect of Sintering Temperature

CoCrFeMnNi high-entropy alloy (HEA), as a typical FCC single-phase high-entropy alloy, is one of the most maturely studied and most promising to be the first to realize industrial applications. However, the CoCrFeMnNi HEA prepared by different processes exhibits significant differences in structure and properties, there also have been few comprehensive evaluations of its overall service performance. In this study, CoCrFeMnNi HEAs were prepared at different sintering temperatures via Fast Hot-Pressed Sintering. The effects of sintering temperature on the microstructure, mechanical properties, tribological properties, corrosion and hydrogen embrittlement resistance of CoCrFeMnNi HEA were comprehensively and systematically studied. With the increase of sintering temperature, the density of the high-entropy alloy increases. The sintering temperature of 1000 degrees C has the most outstanding mechanical properties, with tensile strength and final elongation of 678 MPa and 58% respectively. After the sintering temperature reaches 900 degrees C, the density of the high-entropy alloy reaches more than 95%, and the wear rate is around 8.2 x 10-4 mm3 N-1 m-1. The high-entropy alloy at a sintering temperature of 1000 degrees C has the lowest self-corrosion current density (2.75 x 10-8 A/cm2). Its corrosion resistance is two orders of magnitude higher than that of as-cast CoCrFeMnNi HEA, which is due to its dense structure and small grain size. This study provides a more comprehensive theoretical basis and practical guidance for the preparation and application of CoCrFeMnNi HEAs by powder metallurgy.