Multi-scale construction of subgrain-ultrafine grain-layered matrix structure enhances the strength and plasticity of Mo-TiC alloy

Different from the traditional single strategy of strengthening molybdenum matrix, we designed a full chain preparation process to regulate the Mo-TiC alloy matrix at three scales. Refining the grain size of traditional large-sized molybdenum alloy from >10 μm to <3 μm lays the foundation for high strength. Next, optimizing the dislocation distribution to generate subgrain boundaries at lower scales and layered structures of low/high defect grain regions at higher scales. The subgrain boundaries with high stability due to ultrafine grain pinning could first pin dislocations and indirectly slow down the dislocation accumulation at grain boundaries. Furthermore, the cracks restricted by layered structure tend to propagate longitudinally, which reduces local stress concentration and promotes further stress dispersion through long-distance plastic deformation. Based on the above factors, the Mo-TiC alloy possesses a combination of high strength (792.9 MPa) and excellent plasticity (26.2%), which provides a new perspective for preparing high-performance refractory alloys.