Thermodynamic stability and mechanical properties of (V, M)C (M = W, Mo and Cr) multicomponent carbides: A combined theoretical and experimental study

Abstract

Vanadium carbides (VCs) usually function as reinforced phases of metallic materials, and their elastic and ductile-brittle properties are essential for mechanical properties of bulk materials. In this work, a multi-alloying method is adopted to modify physical properties of VCs. The stability, mechanical and electronic properties of multi-component (V, M)C (M = W, Mo and Cr) carbides were investigated by both first-principles calculations and nano-indentation experiments. The results show that W stabilizes (V, W)C while Cr destabilizes (V, Cr)C as demonstrated by the calculated formation energy. Doping with an appropriate amount of W, Mo and Cr may produce larger ratios of bulk modulus to shear modulus (B/G) and thereby enhance the ductility of (V, M)C carbides according to the Pugh’s criteria while retaining high hardness. The nano-indentation measurements confirm the W doping effect on mechanical properties and agree well with the calculations. The physical properties of doped (V, M)C carbides can be rationalized by the evolution of intrinsic chemical bonding as suggested by the electronic structures.