Preparation and Characterization of In Situ (TiC-TiB₂)/Al-Cu-Mg-Si Composites with High Strength and Wear Resistance

This study involved the preparation and characterization of in situ (TiC-TiB₂)/Al-4.7Cu-0.32Mg-0.44Si composites with excellent mechanical and abrasive wear properties. The composites were synthesized in an Al-Ti-B₄C system by combining combustion reaction synthesis with hot-pressed sintering and hot extrusion. The in situ TiB₂ and TiC particles were of multi-scaled sizes ranging from 20 nm to 1.3 μm. The TiB₂ and TiC particles effectively increased the yield strength (σ_0.2), ultimate tensile strength (σ_UTS), hardness (HV), and abrasive wear resistance of the composites. The 40 wt.% (TiC-TiB₂)/Al-4.7Cu-0.32Mg-0.44Si composite exhibited the highest σ_0.2 (569 MPa), σ_UTS (704 MPa) and hardness (286 HV), which were 74%, 51% and 110% higher than those of the matrix alloy, respectively. Compared with the matrix alloy, the abrasive wear resistance of the 40 wt.% (TiC-TiB₂)/Al-4.7Cu-0.32Mg-0.44Si composite was increased by 4.17 times under an applied load of 5 N and Al₂O₃ abrasive particle size of 13 µm. Micro-ploughing and micro-cutting were the main abrasive wear mechanisms for the Al-Cu-Mg-Si alloy and the composites.