Strength-ductility synergy in a graphene oxide reinforced aluminum matrix composite made by friction stir processing

The present study examines the influence of carbonaceous reinforcement (graphene oxide, GO) on the microstructural and mechanical properties of aluminum (Al) matrix composite fabricated by single-pass friction stir processing (FSP). GO reinforcement is introduced to the metal matrix by adhesively attaching GO powder to the surface of pure Al plates. The presence of GO within the Al matrix is initially characterized using Raman spectroscopy and secondary ion mass spectrometry, followed by detailed analysis using scanning electron microscopy and transmission electron microscopy. Due to dynamic recrystallization, significant grain refinement occurs in both FSP-treated Al alloys with and without GO conditions. However, the grains are more refined for FSP-GO condition, as the extent of dynamic recrystallization changed due to the dispersion of GO within the Al matrix. The presence of GO and its interaction with Al alloys during FSP develop superior mechanical properties (higher yield and tensile strength with greater ductility) compared to the BM and FSP-treated Al (FSP-only) conditions. The microhardness distribution shows the most hardened region on the advancing side of the stir zone, where the GO concentration is relatively high due to material flow occurring during FSP.