Design of novel AlCoFeNiV high-entropy alloys with high-strength and high-ductility

Eutectic high-entropy alloys (EHEAs) are gaining interest due to their excellent mechanical properties, superior liquidity and castability, and reduced compositional segregation. Here, we developed and successfully prepared Al19Co23Fe21Ni37 EHEA using vacuum arc melting. By adjusting the Co content and introducing V, we also obtained near-eutectic high entropy alloys (Al18Co27Fe20Ni35 and Al18Co22Fe20Ni35V5). The Al19Co23Fe21Ni37 and Al18Co27Fe20Ni35 alloys consist of alternating face-centered cubic (FCC) and ordered body-centered cubic (B2) phases, whereas the Al18Co22Fe20Ni35V5 alloy consists of FCC, ordered face-centered cubic (L12) and B2 phases. The heterostructure not only restricts dislocation motion but also induces significant hetero-deformation-induced hardening, resulting in a high-strain hardening effect. Furthermore, the high volume fraction of the hard B2 phase contributes to the increased strength of the alloy due to its high-stress partition relative to the other phases. As such, Al18Co22Fe20Ni35V5 alloy exhibits an excellent tensile ductility of 16.1%, yield strength of 571 MPa, and ultimate tensile strength of 1157 MPa.