Effect of Iron content on the microstructure evolution, mechanical properties and wear resistance of FeXCoCrNi high-entropy alloy ‎system produced via MA-SPS

Abstract

Abstract In the present study, the FexCoCrNi (x = 1, 1.3, 1.6) high entropy alloy (HEA) system was prepared by mechanical alloying (MA) and spark plasma sintering (SPS). The effect of iron content on the microstructure, mechanical properties, thermal behavior, and wear resistance of the FexCoCrNi (x = 1, 1.3, 1.6) HEA system was separately studied. It was found that all 3 alloys showed body-centered cubic (BCC) and face-centered cubic (FCC) solid solutions after 50 h of milling and an increase in the iron content was accompanied by an increase in the fraction of the BCC solid solution. Thermal stability of the FexCoCrNi (x = 1, 1.3, 1.6) HEA system was evaluated in the temperature range of 973–1273 K. The FCC structure was retained even after thermal exposure at 973, 1123, and 1273 K for all 3 alloys. The increase in Fe content led to a decrease in the sigma phase (FeCr or CoCr) formation temperature. The results of mechanical tests indicated that increasing Fe (1–1.6 mol) resulted in enhancement of ultimate tensile strength and hardness from 480 to 560 MPa and 320–400 Vickers, respectively. Wear resistance results demonstrated that the coefficient of friction (COF) and weight loss of this system decreases with increased Fe content. Moreover, the dominant wear mechanism changed from abrasive wear to adhesive wear.