Assessing the role of reinforcement size and weight  percentage on the mechanical and wear characteristics of Al7050‐TiO2‐hBN hybrid composites

Abstract In the present study, hybrid composites of Al7050 reinforced with TiO 2 (1, 3 and 5%) and hexagonal boron nitride (hBN, 2, 4 and 6%) have been developed by using two different sized reinforcing particles (∼ 40 μ m and ∼ 20 μ m) through stir casting route with an aim to investigate the role of particles size within the micrometer level on mechanical and wear characteristics. From the microhardness measurements, higher hardness was measured for the composites with the increased content of the reinforcement. Similar trend was observed for the composites with both the reinforcement sizes. From the impact strength measurements, more values were observed for the composites having 20 μ m sized reinforcements. With the increased fraction of hBN (6%), no significant improvement in the impact strength was noticed for the composites with 40 μ m sized reinforcements. On the other hand, significant increase in the impact strength was measured for the composites with 20 μ m sized reinforcements. Increased tensile strength (from 95 ± 4.6 up to 156.8 ± 6.1 MPa) with the higher fraction of reinforcements was measured at the cost of losing ductility as reflected in the decreased % of elongation (from 15.2 to 11.65). With the decreased size of reinforcement from 40 to 20 μ m, the composites exhibited more strength and lower ductility. From the wear studies, it was clearly observed a decreased trend in the wear rate and increased coefficient of friction with the increased reinforcement content. Compared with 40 μ m reinforcements, adding 20 μ m sized reinforcements has shown higher level of impact on reducing the wear rate. The results demonstrate that the size difference of reinforcing particles in the level of a few micrometers also significantly affects the performance of the composites.