Strengthening and plasticity improvement mechanisms of titanium matrix composites with two-scale network microstructure

The two-scale network microstructure was designed and achieved in the (Ti₅Si₃ + TiBw)/Ti6Al4V composite by forming submicron-Ti₅Si₃ particle and micron-TiB whisker around α phase and Ti6Al4V particle, respectively. The experimental and simulation results verified that the two-scale network microstructure could bring in excellent tensile properties, compared with single network microstructure and uniform microstructure. The calculation results based on the analytical model showed that the increment was mainly attributed to grain refinement and solution strengthening, which was related to the two-scale network microstructure. Compared with the first-scale network with micron-TiBw, the second-scale network with submicron-Ti₅Si₃ could exploit 10.3% increment in strength. The ductility of the composite was enhanced by 56.3% through submicron-Ti₅Si₃ particle (within the β phase) pining and accumulating dislocation. The finite element analysis and EBSD results revealed that the cooperation effect of two-scale network microstructure improved the deformation compatibility of the composite.