Effect of heat treatment temperature on the microstructure and hardness of AlCoCrNiFe high-entropy alloy sintered by hot oscillating pressing

The effect of heat treatment (HT) temperature on the microstructure and properties of hot oscillating pressing (HOP) sintered AlCoCrNiFe high-entropy alloy (HEA) was studied. Before and after HT, it is basically composed of the BCC and FCC phases. As the HT temperature increases, the original powder interface of HEA gradually disappears and melts, the degree of powder particle bonding is strengthened, and the density is gradually increased. Its microstructure has been improved. However, the content of the BCC phase gradually precipitates to increase, and the thickness of the lamellar phase gradually increases. Therefore, as the HT temperature increases, its Vickers hardness gradually increases, reaching a maximum of approximately 423.6 HV1. However, due to the increase in phase layer thickness, the increase in Vickers hardness gradually slows down at higher HT temperatures. It can be seen that an appropriate HT temperature is beneficial for obtaining high-density and high-performance AlCoCrNiFe HEA.