Improving the Mechanical Properties of Al-Si Composites through the Synergistic Strengthening of TiB2 Particles and BN Nanosheets

The size and distribution of the silicon phase and intermetallic phase are important factors affecting the properties of Al11Si3Cu2NiMg alloy (M142). In this study, BNNS and micro-TiB2 were used to synergistically refine and reinforce M142 composites (M142-BNNS-TiB2). After T6 heat treatment, the comprehensive mechanical properties of M142-BN-TiB2 composites were excellent, with an ultimate tensile strength of 463 MPa and an elongation of 2.6%. In addition, the introduction of BNNS and micro-TiB2 changed the fracture mode of M142 from brittle fracture to quasi-cleavage fracture, and the introduction of BNNS and micro-TiB2 refined the Si phase and intermetallic phase, which could change the origin of the crack in the composite, thus improving the ductility of the composite.