Effect of heat treatment on microstructure, mechanical and tribological properties of Al-based TiB2/ZrO2 reinforced hybrid composites

This study focused to examine the properties of hybrid composites with different weight% of reinforcement particles. Al6082 was taken as a matrix material for the development of hybrid composites, and the combination of TiB2 (1-3%) and ZrO2 (1-3%) was taken as a reinforcement. The hybrid composites were produced by stir casting techniques, and then samples were kept for heat treatment. The optimised T-6 cycle was used for heat treatment. The microstructural and phase analyses were carried out using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. Mechanical characterisation, i.e. (tensile test, microhardness test, and impact test) was performed to know the properties of developed hybris composites. It was seen that the heat-treated samples exhibited 20-40% better properties than as-cast samples. The sample containing 2% TiB2 and 1% ZrO2 showed better mechanical properties than other reinforced samples. However, the sample containing 1% TiB2 and 2% ZrO2 exhibited superior impact energy compared to other developed hybrid composite samples. The dry sliding wear test of samples was conducted by pin-on-disc at a fixed normal load (20 N) and sliding speed (300 rpm). From the wear test, it was observed that the reinforcement particles greatly influenced the wear resistance. The wear rate and coefficient of friction (COF) of heat-treated samples were demonstrated to be 25-40% lower than as-cast samples. Combining 2% TiB2 and 1% ZrO2 hard ceramic reinforcement particles gave a lower wear rate than other combinations. Worn surfaces were also examined by SEM to know the wear mechanism.