Microstructure and Mechanical Property Variation of Al6061/GNP Nanocomposite by Mg and Ultrasonic Vibration in Bottom Pouring Stir Casting

Abstract

Stir casting is a cost‐effective and economical technique for producing aluminum matrix composites (AMCs). However, it is necessary to address the issue of poor wettability and lower interfacial interaction between nanoreinforcing particles and the matrix. Ultrasonically aided solidification is an effective solution to these issues. In the present study, an Al6061/graphene nanoplatelet (GNP) nanocomposite is manufactured using the ultrasonic‐assisted stir casting (USASC) technique. Magnesium (Mg) is added as a wetting agent to reduce clustering and improve the homogeneous dispersion of GNPs in the matrix. A detailed examination of the mechanical and microstructural properties of AMCs synthesized with bottom pouring stir casting (BPSC) and USASC techniques is investigated and compared. The USASC nanocomposite demonstrates better dispersion of the GNP particles and a ≈92% reduction in porosity attributed to enhanced wettability and cavitation effect compared to the BPSC‐based nanocomposite. The USASC‐based nanocomposite shows ≈106, ≈494%, and ≈347% improvement in nanohardness, ultimate tensile strength, and yield strength, respectively, compared to the BPSC nanocomposite. The scanning electron microscope fractograph of the USASC‐based nanocomposite reveals a mixed kind of brittle–ductile failure mechanism. Theoretical calculations of yield strength indicate that the load transfer, followed by coefficient of thermal expansion mismatch, significantly contributes to the strengthening of the nanocomposite compared to other mechanisms.

Topics & Concepts