A first principles investigation on the solid solution behavior of transition metal elements (W, Mo, Ta, Cr) in Ti(C,N)

The stability, mechanical properties and electronic structure of (TiyM1-y)(C,N) with different M atoms(M = W, Mo, Cr, Ta) and amonts are theoretically studied by Density Functional Theory (DFT). The calculated results of the stability of (TiyM1-y)(C,N) suggest that M atom prefer to bond with C atom and occupy the metal atomic site surrounding by C atom in (TiyM1-y)(C,N) during the solid solution process. The calculated results of structures of (TiyM1-y)(C,N) supercell with different amount of M atom elucidate that appropriate W/Mo addition can slight shrink the lattice and Cr addition can distinctly play the same role, but Ta atom in (TiyM1-y)(C,N) plays a contrary role. The calculated mechanical properties and electronic structures of (TiyM1-y)(C,N) show that W/Mo addition can improve mechanical properties of (TiyM1-y)(C,N) due to the strong polar covalent bond between W/Mo and C atoms and mechanical properties of (TiyCr1-y)(C,N) deteriorates can be attributed to the weak covalent bond between Cr and C atom. Meanwhile, strong Ta-C covalent bond can improve mechanical properties of (TiyM1-y) (C,N) under appropriate Ta addition, excessive existence of Ta atom can rob electrons from Ti-C bonds to weaken them, which is harmful to mechanical properties of (TiyM1-y)(C,N).

Automated summary

The stability, mechanical properties, and electronic structure of (TiyM1-y)(C,N) with different M atoms and amounts were theoretically studied using Density Functional Theory (DFT). The results showed that different metal atoms have varying effects during the solid solution process and on the lattice structure and covalent bond strength of C atoms. The addition of appropriate amounts of W/Mo and Ta can improve the mechanical properties of (TiyM1-y)(C,N), while excessive Ta can weaken the Ti-C bonds and deteriorate the mechanical properties.