Effect of Ti addition in the matrix on the microstructure and properties of SiCp/Al composites

To address the performance degradation of silicon carbide particle-reinforced aluminum matrix composites (SiC p /Al) caused by adverse interfacial reactions during the preparation of large billets via pressureless infiltration—specifically due to prolonged holding time and excessive temperature—this study optimizes interfacial characteristics and microstructure by adding Ti to the aluminum matrix. SiC p /Al composites with varying Ti content (0–2.5 wt%) were prepared using pressureless infiltration, and the effects of Ti addition on microstructure and mechanical properties were systematically analyzed. Results show that Ti reacts with SiC at the interface to form TiC and Ti 5 Si 3 phases, effectively suppressing the formation of the brittle Al4C3 phase. Additionally, Ti enrichment at the interface refines α-Al grains and eutectic Si structures. At 1.5 wt% Ti, the composite exhibits a 5.28 % increase in flexural strength (from 425.45 MPa to 448.65 MPa) and an 11.82 % improvement in hardness (from 208 HB to 231 HB). Excessive Ti (>1.5 wt%) induces Al3Ti phase coarsening and matrix fragmentation, leading to performance deterioration. This work reveals the dual mechanisms of interfacial reaction regulation and grain refinement by Ti in enhancing SiC p /Al composites, providing a theoretical basis for optimizing aluminum matrix composite interface design.