Effects of TiB2 content on microstructural evolution, microhardness and tribological behaviours of Al matrix composites reinforced with TiB2 particles

In this study, Al2024/TiB2 composites with different TiB2 fractions (5, 10 and 15 vol%) were fabricated by highenergy ball milling and spark plasma sintering. The effects of TiB2 fraction on the microstructure, hardness and wear resistance of the composites were explored to determine the optimal TiB2 content in the composite with optimal properties. An increase in Vickers hardness of the composites correlates with the increased TiB2 content, and the Al2024-15TiB2 composite exhibits the highest hardness. The wear rate of the composite initially increases and then decreases with higher TiB2 content. Notably, the Al2024-10TiB2 composite demonstrates the best wear resistance with a wear rate of 1.14 x 10-4 mm3/Nm, representing a 96.81 % reduction compared to the unreinforced Al2024. The deteriorated wear resistance of the Al2024-15TiB2 composite was attributed to the decreased toughness and severe three-body abrasion caused by the excessive TiB2 particles.