Synthesis and evaluation of rocksalt structure (Mo, W) carbides via vanadium additions

Abstract

The mechanical properties of rocksalt (B1) binary, ternary, and high entropy transition metal ceramics exhibit strong correlation with their valence electron concentration (VEC). With respect to maximizing ductility and hardness, it has been proposed that materials with VEC values between 9 and 10 will generally possess superior performance. While many of the transition metal cations inherently crystallize in the B1 structure, the VEC=10 Group-VIB elements don't form room temperature stable B1 carbides. This work demonstrates the ability to stabilize bulk, spark plasma sintered samples of the Group-VIB containing carbides with VEC values in this range. The stabilization of molybdenum and tungsten carbide as room-temperature B1 structures via the addition of different amounts of vanadium and nanoindentation measurements correlated with VEC are the primary goals of this work. The minimum atom percent vanadium to form a single-phase B1 carbide is thoroughly explored and verified via a combination of XRD, EDS, and EBSD.