Enhanced wear resistance of a multi-phase reinforced Al0.5CrFeNi2.5Si0.25 high-entropy alloy via annealing

In this work, a multiphase reinforced non-equiatomic Al0.5CrFeNi2.5Si0.25 high -entropy alloy (HEA) was prepared by vacuum induction melting. The effect of heat -treatment temperature (1023, 1123, 1323, and 1473 K) on the microstructure, mechanical properties, and wear behavior are systematically investigated. The results indicate that the as -cast and annealed alloys are composed of face -centered cubic (FCC) and body -centered cubic (BCC) structures accompanied by microscale and nanoscale precipitated phases. To be specific, the FCC matrix is enriched in the L12 phase, and BCC particles and sigma phases are observed in the B2 matrix. The microstructure of Al0.5CrFeNi2.5Si0.25 HEAs consists of dendritic region (DR) and inter-dendritic (ID) region before and after annealing. The phases and microstructure did not change. After annealing, the size of the Cr-rich BCC particles is reduced. The L12 phase has a density per unit area that first increases and then decreases, reaching its highest density at 1123 K. With the annealing temperature rising, the nanohardness increases slightly and then decreases, reaching a peak value of about 6.29 GPa at 1123 K. The Al0.5CrFeNi2.5Si0.25 HEA annealed at 1123 K also exhibits the lowest specific wear rate of 2.43 x 10-4 mm3/Nm, which is decreased by 23.5% compared to the ascast one.