A strategy for enhancing the mechanical property of the precipitation-strengthened medium-entropy alloy

Medium-entropy alloys strengthened by the L1₂-type coherent precipitates were recently proposed, whereas the mechanical property still needs to be improved. Here, we demonstrated a strategy for notably improving the strength of the representative (CoCrNi)₉₄Ti₃Al₃ alloy, in which the refinement of grain structures and the promotion of precipitation were concurrently achieved by pre-strain followed by aging. A refined grain structure containing incoherent σ-precipitates and a large number of coherent L1₂-precipitates was formed, which enhances the yield strength and ultimate tensile strength up to 1431 MPa and 1683 MPa respectively. Furthermore, decreasing pre-strain temperature or increasing strain further aids the enhancement. The present study opens an avenue for fabricating high-performance precipitation-strengthened alloys.