Theoretical study on the lattice distortion and electronic structure in the Al–Co–Cr–Fe–Ni multicomponent alloys

At present, the phase structure design for multicomponent alloys (MCAs) is mainly based on the valence electron concentration (VEC). In this work, based on the classification of valence electrons by the empirical electron theory of solid and molecule (EET), the VEC is further dissected and found that the covalent electron concentration (CEC) can be used as a criterion for determining the phase structure of MCAs. The Alx(CoCrFeNi)1-x (x = 0, 1/24, 1/12 and 1/8) alloys are designed on the basis of the CEC. The effect of Al content on the lattice distortion in the FCC phase of the alloys by combining density functional theory (DFT) and EET. The results show that the degree of lattice distortion in the FCC phase gradually increases with the increase of Al content and the interatomic bonding decreases before the phase structure transition. The alloy reaches the criticality of the phase structure transition when the Al content is 9.48 at.%. The covalent electron concentration (CEC) can be used as a criterion for the phase structure. Based on the CEC, we design Alx(CoCrFeNi)1-x and discuss the effect of Al content on the lattice distortion of the alloy by combining the density functional theory (DFT) and EET calculations, which show that the degree of lattice distortion gradually increases with the increase of Al content and the interatomic bonding decreases. [Display omitted] •CEC stripped from VEC can be used as a criterion for the phase structure of MCAs.•Lattice distortion of FCC phase increases with increasing Al content before transition.•The effect of lattice distortion on the FCC phase is related to covalent electrons.