Attaining superior high-temperature strength in (TiC + (TiZr)5Si3)/TA15 composites through spark plasma sintering and heat treatment

To further enhance the mechanical performance of as-sintered (TiC + (TiZr)₅Si₃)/TA15 composites, this study explores the influence of heat treatment on their microstructure and mechanical behavior. Following solution treatment at 1100 °C for 30 min and subsequent water quenching, the matrix transforms entirely into α′ martensite. The TiC particles retain a stable quasi-continuous network distribution, while the (TiZr)₅Si₃ particles dissolve back into the matrix. After quenching, the composite achieves outstanding compressive properties at room temperature, including a yield strength of 1442 MPa, an ultimate compressive strength of 2178 MPa, and a fracture strain of 25.8 %. At 650 °C, it demonstrates a tensile strength of 835 MPa and an elongation of 18.5 %. Subsequent aging at 600 °C for 300 min results in the α′ martensitic structure without significant decomposition, and (TiZr)₅Si₃ particles re-precipitate within the quasi-continuous network. After solution + aging treatment, the room-temperature compressive yield strength increases to 1617 MPa, representing a 35.0 % improvement over the as-sintered condition. At 650 °C, the tensile strength rises to 887 MPa, marking a 51.6 % increase compared to the as-sintered composite. The remarkable enhancement in mechanical performance following heat treatment is primarily attributed to the combined effects of α′ martensite strengthening, dislocation strengthening, and solid solution strengthening.