Exploring the phase stability, mechanical and thermodynamic properties of FeCrAl ternary alloy

Abstract

Although FeCrAl ternary alloy is a promising high-temperature material, the structural features of the FeCrAl remains controversial. To understand the structural features and the related mechanical properties, here, we apply the first-principle method to study the structural stability, mechanical and thermodynamic properties of FeCrAl ternary alloy. Two FeCrAl phases: cubic and orthorhombic structures are designed and discussed. The calculated results show that two FeCrAl ternary alloys are thermodynamically stable at the ground state. In particular, the orthorhombic FeCrAl has better thermodynamically stable in comparison to the cubic FeCrAl. It is found that two FeCrAl ternary alloys exhibit mechanical stability based on the Born stability criteria. Importantly, we predict that two FeCrAl ternary alloys show ductility and plasticity. The orthorhombic FeCrAl shows the stronger volume deformation resistance and higher elastic stiffness in comparison to the cubic FeCrAl. Naturally, the high elastic modulus of the orthorhombic FeCrAl is related to the strong localized hybridization between Fe atom, Cr atom and Al atom in a layered structure. Finally, it is found that the calculated Debye temperature of the orthorhombic FeCrAl is higher than the cubic FeCrAl.