Unveiling the effect of Ti3O5 nanoparticles on the microstructure elevation and mechanical properties of ultrafine-grained Mo composites

The grain boundary control is requisite in the development of high-performance molybdenum (Mo) composites in the field of high-temperature applications. Meanwhile, strengthening these Mo-based materials without sacrificing their plasticity has been a huge challenge. In this study, we introduced TiC nanoparticles into the Mo alloy system to break the development bottleneck of the mechanical alloying (MA) approach: a large amount of oxygen impurities and large-size second-phase particles at grain boundaries (GBs). Unlike traditional oxides, TiC could undergo a purification effect to absorb a large number of oxygen impurities to generate in-situ and dispersed Ti 3 O 5 nanoparticles during the high-temperature SPS process. First-principles calculations also elucidated that these semi-coherent Ti 3 O 5 nanoparticles could enhance the interface bonding strength of the Mo GBs on account of the stronger Mo-Ti-O bonds. As a result, the average grain size of Mo-Ti 3 O 5 composite fabricated via spark plasma sintering (SPS) technology at 1200 °C is only 1.3 μm owing to the uniform dispersion of nanoscale second-phase particles. Meanwhile, our prepared ultrafine-grained Mo-Ti 3 O 5 composites possess outstanding mechanical properties, where the compressive yield strength, total strain-to-failure, and hardness of the Mo-Ti 3 O 5 composite are 1340 MPa, greater than 50 %, and 362.8 HV 0.5 , respectively. Our strategy using core-shell composite powder as a raw material provides a novel perspective for the preparation of high-performance refractory metals and has potential to be applied to relevant engineering applications.