L21-strengthened body-centered-cubic high-entropy alloy with excellent mechanical properties

Introducing the second phase into high-entropy alloy through composition design is an effective strategy to further improve its mechanical properties. In this work, a novel Fe35Cr35Ni15Al12Ti3 HEA was successfully designed and prepared with arc-melting method. Its microstructure, phase constitution, mechanical properties, and strengthening mechanisms were systematically investigated. A uniform distribution of high-density semi coherent L2(1) and coherent B2 precipitates in the BCC matrix was achieved. Significantly, the HEA possesses outstanding mechanical properties, with true compressive yield strength of 1308.0 MPa, maximum compressive strength of 1803.8 MPa and maximum compressive strain of 86.8%, which are much higher than most similar HEAs reported previously. The excellent mechanical properties could be ascribed to the precipitation strengthening and solid-solution strengthening induced by fine B2 and uniform distribution of L2(1) precipitates.