Enhanced mechanical properties of NiCoCrCuAl high entropy alloys with dual-phase microstructure

Abstract

The correspondence between the mechanical properties and the microstructure of NiCoCrCuAl series high-entropy alloys (HEAs) was investigated by the adjustment of face-centered cubic (FCC) and body-centered cubic (BCC) phase proportions. The results show that the NiCoCrCuAl HEAs changed from FCC to BCC phase, with the volume fraction of body-centered cubic (BCC) phase increasing from 14 % to 93 %. The microstructure of the alloys evolves from typical dendritic structure to fine equiaxed grains. The hardness of 518 Hv and the ultimate tensile strength of 1092 MPa were achieved in the NiCoCrCuAl series HEAs. The phase composition and microstructure were comprehensively analyzed based on the mixing entropy and enthalpy, atomic size, valence electron concentration, and electronegativity. The mechanical properties were analyzed from the perspective of mixture of FCC and BCC phases.