A new strategy for enhancing the work hardening ability and strength of FCC high entropy alloys: Simultaneously regulating the stacking fault energy and precipitated phases

High-entropy alloys (HEAs) with face-centered cubic crystal structure (FCC) usually have good ductility but relatively low strength. In this work, we propose a new strategy to address the insufficient strength of FCC structured HEAs. The strategy is carried out in two ways: (1) By reducing the stacking fault energy of alloy system to improve its work hardening ability; (2) By adjusting the content of alloying element to control the quantity of L1₂, σ and κ phases, thereby strengthening its matrix. Based on the above ideas, the non-equimolar Fe₂CoNiV_x HEAs were designed by adjusting the element content of the classic FeCoNiV HEA. The results show that Fe₂CoNiV_1.3 alloy has excellent work-hardening ability and strength, of which work hardening index is improved by 36 %, the yield and fracture strength are increased by 12.6 % and 40.8 % compared to FeCoNiV HEA, respectively. Additionally, the Fe₂CoNiV_1.3 alloy also has the best comprehensive mechanical properties. Its yield strength, ultimate tensile strength and elongation are 315.5 MPa, 724.2 MPa and 33.9 %, which is superior to the vast majority as-cast FCC structured HEAs. This study not only reduces the cost, improves the alloy's strength and toughness, but also provides ideas for the composition design of new advanced HEAs.