Microstructure Evolution and Mechanical Properties of Ultra-Fine Grain AlCrFe 2 Ni 2 W x High-Entropy Alloys

Ultra-fine grain AlCrFe 2 Ni 2 W x (x = 0.1, 0.2, 0.3, 0.4) alloys were designed and prepared by vacuum arc melting, and corresponding microstructural evolution and mechanical properties were investigated. All of the alloys show a mixed structure with FCC + BCC (B2) + TCP phases. The addition of W element has a significant effect on the formation mechanism of the morphology, which promotes the transition from FCC phase to μ phase and inhibits the spinodal decomposition of BCC phase. With the increase of W content, more μ phase precipitates from the FCC phase and grain boundaries. After the dissolution of W element into matrix, the formed oversaturated solid solution and precipitated μ phase have the effect of solid solution strengthening and second phase strengthening, respectively. The yield strength and Vickers hardness increases from 765 to 1319.6 MPa and HV 332.2 to HV 461.8, respectively. The addition of W element enhances the strength of the alloys but reduced ductility. The AlCrFe 2 Ni 2 W 0.1 alloy exhibits outstanding comprehensive mechanical properties, with its fracture strength reaching 2726.5 MPa and a considerable compressive strain of 43.3%, which implies promising potential engineering application. Graphical abstract