First-principles investigations on the electronic structures, polycrystalline elastic properties, ideal strengths and elastic anisotropy of U3Si2

Abstract

First-principles calculations based on density functional theory with on-site Coulomb correction were used to examine the electronic structures, polycrystalline mechanical properties, ideal tensile and shear strengths and elastic anisotropy of U3Si2. The present lattice parameters and elastic stiffness constants of single crystal are in good agreement with the experimental data and other theoretical results. Density functional perturbation theory method was used to obtain the dynamical properties of U3Si2, and the well-known Born criteria was investigated to prove the structural stability of the ideal strength calculation model. Also, Voigt–Reuss–Hill model was used to evaluate the polycrystalline properties such as Young’s modulus, the shear modulus, the bulk modulus and so on. The semiempirical formulas for the theoretical estimation of the Debye temperature were adopted. The first-principles computational tensile test (FPCTT) was used to explore the ideal tensile strengths along typical crystal orientations and the ideal shear strengths in several slip systems of P4/mbm U3Si2. Additionally, the elastic anisotropy of P4/mbm U3Si2 was characterized by several anisotropic factors and directional moduli. Within the elastic strain range, the Poisson’s ratios under different single loads were obtained. The least-squares method was used for polynomial fitting of the data obtained by FPCTT method, and the results were satisfactory. These calculated results help to understand the nature of U3Si2 better and provide more useful information to design and develop U3Si2 for a new fuel-cladding solution. The relation curves between stress and strain of U3Si2 were obtained and the ideal tensile and shear strengths of U3Si2 were predicted.