Effects of Ti5Si3 characteristics adjustment on microstructure and tensile properties of in-situ (Ti5Si3+TiBw)/Ti6Al4V composites with two-scale network architecture

Ti6Al4V matrix composites reinforced with needle-like Ti5Si3 particles distributed in the secondary-scale network and TiB whiskers in the first-scale network were in-situ synthesized using reaction hot pressing. In order to adjust Ti5Si3 characteristics and improve the mechanical properties of the composites, effects of sintering parameters on microstructure and tensile properties were systematically investigated. The size, distribution and morphology of the Ti5Si3 precipitation can be adjusted by controlling the sintering parameters. The quantity of the Ti5Si3 precipitation in the secondary-scale network (β-Ti phase) increased significantly with increasing temperatures. Moreover, compared with the sintering time, the sintering temperature plays a more dominant role in controlling the microstructure and tensile properties of the composites. The composites fabricated at 1300 °C for 1.5 h exhibited enhanced tensile properties at both room and elevated temperatures with more and finer Ti5Si3 distributed in the secondary-scale network.