Effect of nano-sized precipitates on the fatigue property of a lamellar structured high entropy alloy

Fatigue damage is inevitable and destructive for in-service structural materials and hence warrants a detailed examination of the fatigue behavior of potential structural materials such as high entropy alloys (HEM). This study focused on investigation of the mechanical properties of Al0.7CoCrFeNi HEA with two microstructural conditions; i.e., a lamellar structure consisting of FCC + B2 phases (a) without precipitates and (b) with nano sized L1(2) precipitates in the FCC phase. Nano-sized L1(2) precipitates were introduced in FCC through low-temperature annealing. Although the nano-sized L1(2) precipitates enhanced tensile strength, no improvement in fatigue properties was noted. For both conditions, crack initiation and propagation were observed along persistent slip bands and FCC/B2 phase boundaries.