The characteristics and mechanical properties of Mo/VC interface structures via first-principles calculations

Abstract

In the present work, 15 Mo/VC interfaces were investigated using first-principles calculations based on density functional theory. Four possible interface orientations, two terminations, and three stacking sites were considered. The adhesion energy (Wad) and interfacial energy (Eint) of these interface models were computed. The results indicate that the C-terminated hollow-site Mo(110)/VC(111) interface exhibits the highest stability with a larger Wad value of 10.64 J m−2 and the lowest Eint value of 2.98 J m−2, followed by the V-terminated central-site Mo(211)/VC(220) interface. Analysis of the electronic structure reveals the formation of strong polar covalent bonds at these interfaces. Additionally, simulations of tensile fracture processes were performed, demonstrating that at strains reaching 22% and 32%, respectively, the ideal tensile strengths for the C-terminated hollow-site Mo(110)/VC(111) interface and V-terminated central-site Mo(211)/VC(220) interface are ∼26.01 and 35.53 GPa. In particular, in the C-terminated hollow-site Mo(110)/VC(111) interface, fracture occurs in the Mo slabs due to concentrated strain when external strain is applied; meanwhile, uniform strain is observed in both Mo(211) and VC(200) slabs within this system. Notably, the V-terminated central-site Mo(211)/VC (220) interface demonstrates excellent tensile strength as well as toughness. These findings suggest that explaining solely based on adhesion work is insufficient to account for the observed tensile strength at these interfaces.