Microstructure Evolution and Strengthening Mechanism of AlCrFe₂NiCuMo_x High Entropy Alloys

The AlCrFe₂NiCuMo_x multiphase high entropy alloys were designed, prepared and characterized. The effect of Mo addition on the microstructure evolution and mechanical properties of AlCrFe₂NiCuMo_x high entropy alloys was investigated. The microstructure of AlCrFe₂NiCuMo_x alloy consists of B2 + BCC + FCC + σ phases with a typical dendritic morphology. The addition of the Mo element promotes the generation of the σ phase in the alloy, while the B2 phase is gradually replaced by the σ phase. The hardness test and room temperature compression test results show that AlCrFe₂NiCuMo_0.6 alloy has a compressive rupture strength of 2030 MPa, a yield strength of 1462 MPa, a compressive strain limit of 18.18%, and a hardness of 488 HV, which has good comprehensive mechanical properties. With the increase of Mo element addition, the BCC solid solution phase and the ordered B2 phase separated in the alloy, and the σ phase precipitate from the BCC solid solution phase, and the mechanical properties of the alloy become worse at room temperature.