Evolution of Microstructure and Mechanical Properties of As-Cast Al_xCrFe₂Ni₂ High-Entropy Alloys with Al Content

This study designed a series of low-cost Al_xCrFe₂Ni₂ high-entropy alloys with different Al contents (x = 0.1-1.0 at.) and investigated their microstructure and mechanical properties. The XRD analysis revealed that, with an increase in the Al content, their crystalline structures changed from the initial single face-centered cubic (FCC) one to FCC plus body-centered cubic (BCC) and ordered BCC (B2) structures. The tensile strength and hardness first increased and then dropped with increasing Al content related to the volume fraction of the FCC/BCC phase. At x = 0.9, the as-cast alloy containing 49.1 pct BCC phase exhibited the highest ultimate tensile strength of 1278 MPa with a 12.6 pct ductility. With an increase in the Al content, the alloy fracture mechanism changed from ductile fracture to brittle.