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

Abstract

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 TaC covalent bond can improve mechanical properties of (TiyM1-y)(C,N) under appropriate Ta addition, excessive existence of Ta atom can rob electrons from TiC bonds to weaken them, which is harmful to mechanical properties of (TiyM1-y)(C,N).