Development and characterization of Al5083-CNTs/SiC composites via friction stir processing

Carbon nanotubes (CNTs) and or micron-sized silicon carbide (SiC) particles were reinforced with Al5083 matrix to develop mono and hybrid composites via friction stir processing (FSP). The effect of CNTs/SiC either individually or in aggregate form, on microstructural evolution, texture, and mechanical properties of friction stir processed (FSPed) Al5083 composites were studied. EBSD and TEM analyses revealed an equiaxed recrystallized microstructure and dislocations rearranged to form high angle grain boundaries (HAGBs) upon dynamic recrystallization (DRX), respectively. The overall weak texture intensity was observed across the stir zone of FSPed samples due to the multiple passes. Incorporation of CNTs/SiC particles in Al5083 matrix resulted in the activation of Zener-Holloman mechanism and particle-stimulated nucleation (PSN) mechanism by developing randomly oriented grains. In FSPed composites, SiC particles are dispersed homogeneously with good interfacial bonding and CNTs are partially reacted with an Al5083 matrix to form in-situ Al4C3 intermetallic compound. The maximum tensile strength of 361 MPa was obtained for Al5083-CNTs/SiC hybrid composite. The fracture surface of the SiC reinforced composite revealed that the voids initiation at the matrix-particle interface regions.