Graphene sheets encapsulating SiC nanoparticles: A roadmap towards enhancing tensile ductility of metal matrix composites
In this study, β-SiC nanoparticles were well dispersed in a matrix of aluminium making use of encapsulation capacity of graphene sheets, semi-solid stirring of the aluminium melt, ultrasonic treatment, and pressure application during solidification. A new solidification model taking into account the alteration of the solidification mechanism from particle pushing to particle engulfment, making use of at least 40% enhancement in higher thermal conductivity and diminished repelling forces of SiC nanoparticles tuned by encapsulating graphene sheets was suggested. This nanostructure manipulation can make about 350% and 258% enhancement in yield strength and tensile ductility, respectively, compared to that of unreinforced aluminum alloy. The results achieved based on the devised analytical model have shown the significant effect of thermal activated dislocation in strengthening due to considerable mismatch between thermal expansion coefficient of graphene sheets and aluminium matrix. Fractographic observations disclosed a dimple fracture surface for the semi-solid-processed aluminium matrix composite reinforced by the nanoparticles that were encapsulated by graphene sheets using ball-milling process compared with the cleavage fracture surface of those fortified without the application of graphene.