Critical Assessment 43: Microstructural and mechanical properties of friction stir additively fabricated SiC-Reinforced AA6061 build

Friction stir additive manufacturing was employed to fabricate a SiC-reinforced AA6061 composite. The tool with a pin length of 4.5 mm (plunge depth of 50% into the lower layer thickness) was used for the experiment. The stir zone consisted of fine, equiaxed grains due to dynamic recrystallisation. Variations in grain size, as well as changes in precipitate distribution, size, and morphology, were detected along the build direction. Hardness and tensile strength varied across layers, with the top slice having the greatest values of 104.2 HV and 268.4 MPa, respectively. Notably, the FSAM build demonstrated improved ductility with a maximum of 58.98%, mostly ascribed to fragmentation and partial loss of grain-boundary phases, as well as strong interfaces that delayed necking.