LAUSR

Abstract Al0.7CoCrFeNi high-entropy alloy (HEA), as a promising material, has attracted growing interest. This study aimed to investigate the effect of phase transformation in non-equilibrium Al0.7CoCrFeNi HEA on its properties and densification kinetics during spark plasma sintering (SPS). We found that the BCC-to-FCC phase transformation causes a grain size reduction from 5.66 to 3.10 μm, while decreases the Vickers hardness from 372.5 ± 4 to 328.4 ± 3 HV. The decreased Vickers hardness reduces the wear resistance with the volume wear rate increasing from 1.583 × 10−4 to 2.108 × 10−4 mm3·N−1·m−1. Besides, the BCC-to-FCC phase transformation improves the ductility from 2.5 ± 0.4 to 8.4 ± 0.3%. The further precipitation of a θ phase observed in the sample sintered at 1100 °C improves the ultimate tensile strength from 856.1 ± 13 to 1053.7 ± 8 MPa, although the ductility decreases from 8.4 ± 0.3 to 7.3 ± 0.3%. Interestingly, we also observed that the BCC-to-FCC phase transformation reduces densification kinetics, because it decreases the diffusion coefficient.