First-principles study of the structural and elastic properties of Ti₅Si₃ with substitutions Zr, V, Nb, and Cr

The formation enthalpy, electronic structures, and elastic moduli of the intermetallic compound Ti₅Si₃ with substitutions Zr, V, Nb, and Cr are investigated by using first-principles methods based on the density-functional theory. Our calculation shows that the site occupancy behaviors of alloying elements in Ti₅Si₃, determined by their atom radius, are consistent with the available experimental observations. Furthermore, using the Voigt–Reuss–Hill (VRH) approximation method, we obtained the bulk modulus B, shear modulus G, and the Young’s modulus E. Among these four substitutions, the V, Nb, and Cr substitutions can improve the ductility of Ti₅Si₃ effectively, while Zr substitution has little effect on the elastic properties of Ti₅Si₃. The elastic property variations of Ti₅Si₃ due to different substitutions are found to be correlated with the Me^4d–Me^4d antibonding and the strengthened Me^4d–Si bonding in the solids.