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

Abstract Ti6Al4V matrix composites reinforced with needle-like Ti 5 Si 3 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 Ti 5 Si 3 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 Ti 5 Si 3 precipitation can be adjusted by controlling the sintering parameters. The quantity of the Ti 5 Si 3 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 Ti 5 Si 3 distributed in the secondary-scale network.