Preparation and In-Situ Strengthening Mechanisms of Wc Reinforced Mo Alloys

Abstract

The strength enhancement is critical for the application exploration of molybdenum alloys. In this work, a novel secondary phase of WC is introduced into the Mo matrix for the first time. 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 alloy, 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 Mo 2 C, 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 crystal growth of Mo, resulting in smaller particle size. More importantly, the Mo 2 C ( [[EQUATION]] ) can gain coherent interfaces with Mo ( [[EQUATION]] 0) to intensify the phase boundary, thus effectively pinning the movement of dislocations. This work paves a way for the design of high-performance alloys through the reinforcement of decomposable secondary phases.

Keywords: Mo-WC alloy, Sintering, Composite strengthening, Coherent interface