Towards enhanced elevated-temperature mechanical properties by regulating the spatial distribution of precipitates in cost-effective multi-principal element alloy

Achieving the simultaneous enhancement of elevated-temperature strength and ductility while maintaining low cost remains a fundamental challenge in structural materials design. To address aforementioned issue, a type of Co-free multi-principal element alloy (MPEA) was designed utilizing an Fe-Cr-Ni system as the economical matrix in this study. Compared to conventional Ni-based superalloys and reported MPEAs, expensive Co and W were substituted with Mo and V to achieve solid solution strengthening and improve the stability of the microstructural, while Al, Ti and Nb were incorporated to promote high-density γ′ precipitation. The microstructural analysis revealed that recrystallization treatment effectively eliminated dislocation networks, which suppressed the precipitation of α-Cr phases, and promoted uniform γ′ precipitation throughout the grains during aging. Using this method, we have designed a low-cost, high-performance MPEA. At 700 °C, the tensile strength and elongation of this alloy were 947.3 MPa and 19.2%, respectively, comparable to those of as-forged GH4169 alloy, yet at only 43.8 % of the raw material cost of GH4169. Theoretical calculation further confirmed that the primary strengthening mechanism in this alloy is the precipitation strengthening of the γ′ phases.