Processing of micro/nano-sized TiC/Ti₅Si₃ hybrid reinforced Ti matrix composites by in-situ reactive sintering and their mechanical properties

An innovative in-situ reaction within Ti/reduced graphene oxide/Si mixture powders by rapid spark plasma sintering process (1100 °C for 5 min, 50 MPa) was applied to produce Ti matrix composites, and the in-situ micro/nano-sized TiC/Ti₅Si₃ hybrid products and its mechanical response was demonstrated. Microstructural observations show that the reduced graphene oxide and refined Si were dispersed in Ti powders, and precipitate the fine microstructure containing TiC/Ti₅Si₃ hybrid particles with the micro/nano size during the rapid sintering process. Si agglomeration formed some larger polygonal Ti₅Si₃ particles. Higher Si added mixtures produced the more Ti₅Si₃ particles, and these Ti₅Si₃ particles were coarsened significantly while the refined TiC/Ti₅Si₃ precipitates were also found. The results of Vickers hardness and compression tests demonstrate that the in-situ micro/nano-sized TiC/Ti₅Si₃ hybrid were beneficial for the hardness and strength enhancement of Ti matrix at the room temperature and 600 °C, and such structure achieved the outstanding hardness (HV 629) and compressive yield strength (room temperature: 2.05 GPa, 600 °C: 359 MPa), attributed to the second-phase hybrid strengthening effects.