Microstructural characterization of in-situ MgAl₂O₄ nanoparticles reinforced Al-2Mg-1Si composite produced using the ultrasonic assisted stir casting process

The ceramic particle reinforced Aluminium Matrix Composites (AMCs) lead to a reduction in ductility due to the restricted plastic flow of the matrix. The present work shows an enhancement in tensile properties without considerable loss in ductility by introducing MgAl2O4 (similar to 100 nm) nanoparticles into Al-2Mg-1Si via ultrasonic cavitation treatment (UCT). The microstructural analysis was carried out using polarized light microscope, SEM/EDS and TEM. MgAl2O4 nanoparticles were distributed uniformly in Al-2Mg-1Si matrix by UCT. The addition of MgAl2O4 nanoparticles significantly refined the grain size and enhanced the tensile strength while retaining the ductility of the nanocomposite. Fractography examination of the tensile tested samples revealed a ductile fracture for Al-2Mg-1Si matrix alloy and a brittle fracture for MgAl2O4 reinforced composites. This difference in fracture behavior is attributed to the cleavage texture present on the fractured surfaces of MgAl2O4 nanocomposites. The wear resistance is significantly increased by adding in-situ MgAl2O4 nanocomposites. Plastic delamination and adhesive wear are the main mechanisms, according to analysis of the worn surface.