Effect of TiB₂ on the Microstructure and Mechanical Properties of TiB₂/Al-5Cu Matrix Composites

Particle reinforcement is a proven approach to optimize the microstructure and enhance the mechanical properties of Al matrix composites. In this work, a total of six compositions of TiB₂/ZL205A(Al-5Cu) composites were fabricated by the mechanical stirring fusion casting process. The effect of TiB₂ particles on microstructure and mechanical properties of composites was explored. The experimental results indicated that the grain structure of the composite material was significantly refined, with relative refinement of 23.3%, 32.1%, 42.4%, 49.5%, and 51.6%, respectively, after the addition of TiB₂. With the increase of TiB₂ content, TiB₂ particles can be better attached near the second phase, while agglomeration occurs easily when the content is too high. The mechanical performance results show that the 2.0 wt.% TiB₂/Al-5Cu composite material has the best mechanical properties, with tensile strength (TS), yield strength (YS), and elongation (EL) of 197.8 MPa, 113 MPa, and 7.35%, respectively. Compared to Al-5Cu matrix alloy, it has increased by 51.5%, 61.4% and 129.7%, respectively. Based on the experimental results, the strengthening mechanism of Al-5Cu composites by TiB₂ particles was discussed in detail.