Silicon nitride assisted carbon nanotubes induced stacking faults and twins in aluminum alloy composite joint

The extensive heat input during welding can generally disrupt the meticulously crafted microstructure of the Al alloy substrate, leading to a marked decrease in the mechanical performance of the traditional joint. Here, we conducted a study of adding silicon nitride and CNTs to form Al composite joints, which not only compensated for the microstructural defects caused by welding, but also improved the tensile strength of the joints by 31%. Importantly, microstructural analysis reveals that there are twinning and SFs in both Al and Al4C3 phase. It was contributed to Al4C3 growth and the reduction in Al alloy SFs energy by CNTs. Moreover, the residual CNTs and Al4C3 phase in the composite joints refined the original precipitation phase network. This work is supposed to provide new insights into the strengthening of composite joints based on SFs and twins.