First-Principles Calculate the Stability, Mechanical Properties and Electronic Structure of Carbide MC, M₂C and M₆C in M50NiL Steel

In this paper, the stability, mechanical properties and electronic structure of carbides in steel were calculated using the first-principles method based on the density functional theory (DFT). Firstly, the MC, M₂C, M₆C (M = Cr, Mo, V, Fe) carbides models were established. Then, different interphases' lattice constants, formation enthalpy, binding energy and elastic modulus were calculated. The stability, hardness, ductility and anisotropy of each phase were finally analyzed. The results show that these phases are stable, and the stability is closely related to the electron loss ability of its metal elements. The stronger the electron loss ability of its metal elements, the more stable the formed phase. As for MC carbides, MoC has the largest bulk modulus and hardness. As for M₂C carbides, the Poisson's ratio of Cr₂C is the smallest, and all phases except for Cr₂C show toughness and ductility. The anisotropy of M₆C carbides is relatively poor.