Plasma arc welding-brazing of aluminum to copper with SiO2 nanoparticles strengthening

Abstract Dissimilar metal of T2 copper and 1060 aluminum alloys were welded by plasma arc welding-brazing method with a lap joint, and SiO2 nanoparticles were added in the welding pool to control the interfacial intermetallic compounds (IMC). The interfacial microstructure and phase composition of the weld joint were identified by scanning electron microscope (SEM) and electron probe microanalysis (EPMA). IMC formation mechanism, weld joint tensile strength, and IMC nanohardness was also discussed. The results show that after adding SiO2 nanoparticles, due to the adsorption of the nanoparticles on the copper surface, the total interface energy between the aluminum liquid and the copper substrate would be reduced, and the wetting angle would be reduced. So that the aluminum melts can have better wetting ability, and the barrier effect of SiO2 nanoparticles formed prevents the further diffusion and reaction of copper atoms and aluminum atoms, and inhibits the growth of the IMC layer to a certain extent. The weld fracture occurred at the aluminum-based material added with nano-SiO2, showing typical dimple morphology. The phase with the highest hardness in the IMC layer is CuAl2. SiO2 nanoparticles exist in the CuAl2 intermetallic compound layer due to the adsorption of nanoparticles.