Construction of an in-situ TiC and (TiZr)₅Si₃ dual-scale network hierarchical structure in titanium matrix composites and its effect on mechanical properties

In this study, the pyrolysis products of polycarbosilane were used as sources of carbon and silicon to synthesize (TiZr)₅Si₃ and TiC reinforcements, enhancing the performance of titanium matrix composites. By controlling the particle scale of the matrix alloy powders, the scale of the reinforcement network structure was successfully manipulated. The microstructural features and mechanical behavior of the (TiC+(TiZr)₅Si₃)/TA15 composite were systematically examined. The findings show that the (TiZr)₅Si₃ and TiC reinforcements create a multi-scale hierarchical network structure within the composite, effectively inhibiting β grains coarsening. The TiC particles have an average size of approximately 3.1 μm, while the (TiZr)₅Si₃ particles are around 95 nm in size. Relative to pure TA15 alloy, the β grains were refined from 474.7 μm to 40.6 μm. Moreover, the strength of the composite decreased as the network structure size increased, with the maximum yield strength reaching 1423 MPa, a 47.3 % improvement over the TA15 matrix. Meanwhile, the maximum hardness reaches 402.1 HV, corresponding to a 15.8 % increase compared to the TA15 matrix. This improvement primarily results from the refined grains and the uniform dispersion of reinforcements, while the composite's plasticity remained nearly unaffected by the network structure dimensions.