Microstructure and mechanical characterization of (B4C+ h-BN)/Al hybrid nanocomposites processed by ultrasound assisted casting

The interest in use of hexagonal boron nitride nanoparticles (h-BN) as reinforcement for aluminium has been growing considerably due to its self-lubricating property, thermal and chemical stability. The aluminium nanocomposites containing different wt.% of B4C nanoparticles and Al-B4C-h-BN hybrid nanocomposites are prepared using stir and ultrasound assisted casting method. The prepared hybrid and nanocomposites are characterized using X-ray diffraction, Atomic Force Microscopy, Scanning Electron Microscopy and Energy Dispersive X-ray Analysis. The mechanical properties of boron based nanoparticles dispersed hybrid and nanocomposites are evaluated using tensile, impact, and microhardness testing. The results of microstructural study reveal uniform distribution, grain refinement and low porosity in the composite specimens. The tensile test results show that there is a significant improvement in tensile strength (67%) of the hybrid nanocomposites compared to the base aluminium matrix. The nanocomposite containing 6 wt.% of B4C nanoparticles shows the maximum values of tensile strength and hardness compared to all other combinations of reinforcements. Hybrid combination of B4C (2 wt.% and 4 wt.%) and h-BN (2 wt.%) nanoparticles reinforced aluminium hybrid nanocomposites shows improvement in impact energy and elongation compared to the nanocomposites. The wear properties of the hybrid nanocomposites, containing 4 wt% B4C and 2 wt.% h-BN, exhibit the superior wear resistance properties compared to the unreinforced aluminium matrix and nanocomposites.