Preparation and in-situ strengthening mechanisms of Mo composites with the addition of WC

Abstract

The strength enhancement is critical for the application exploration of Mo-based materials. In this work, a secondary phase of WC is introduced into the Mo matrix, and the corresponding phase, microstructure and mechanical properties have been studied. It is found that the addition of WC particles can significantly improve the mechanical properties, leading to a high ultimate tensile strength (UTS) of 591.5 MPa and a hardness of 242.7 HV over the sintered Mo–12%WC composite, which are about 21.2% and 49.5% higher than those of pure Mo, respectively. During the sintering, the additive WC particles react with the Mo matrix to in-situ generate W and Mo2C, and the former is dissolved into the Mo matrix to exhibit solid solution strengthening. Besides, the latter hinders the migration of grain boundaries (GBs) to limit the grain growth of Mo, resulting in smaller grain size. More importantly, the Mo2C (1‾2‾1) can gain coherent interfaces with Mo (11‾ 0) to intensify the phase boundary. This work paves a way for the design of high-performance composites through the in-situ reinforcement of decomposable additives.