Novel as-cast AlCrFe₂Ni₂Ti_0.5 high-entropy alloy with excellent mechanical properties

We designed a novel Co-free AlCrFe₂Ni₂Ti_0.5 high-entropy alloy (HEA) that features an excellent combination of strength and ductility in this study. The as-cast AlCrFe₂Ni₂Ti_0.5 alloy showed equiaxed grains undergoing spinodal decomposition, which consisted of ultrafine-grained laminated body-centered cubic (bcc) phases and an ordered body-centered cubic (b2) phase, and some precipitates embedded in the b2 matrix. The bcc and b2 phases also feature a coherent interface. This unique structure impedes mobile dislocations and hinders the formation of cracks, thereby giving the AlCrFe₂Ni₂Ti_0.5 HEA both high strength and plasticity. At room temperature, the as-cast AlCrFe₂Ni₂Ti_0.5 alloy exhibited a compressive yield strength of 1714 MPa, an ultimate strength of 3307 MPa, and an elongation of 43%. These mechanical properties are superior to those of most reported HEAs.