Microstructure characteristics and mechanical properties of Cu/Al laminated metal composites fabricated by electropulsing assisted ultrasonic additive manufacturing

In this paper, electropulsing (EP) technique was employed to enhance the capability of ultrasonic additive manufacturing (UAM) of metals. The microstructure and mechanical properties of Cu/Al laminated metal composites (LMCs) fabricated by EP-UAM and preheating (PH) assisted UAM were comparatively investigated. Results show that by introducing EP into UAM, the synergistic effect of ultrasonic shear and EP is produced, which promotes the plastic flow of Al near the Cu/Al interface, offsetting the negative influence of no-preheating. Compared to the PH-UAM, EP-UAM induces atomic diffusion and formation of a tiny of Cu-Al intermetallic compounds more effectively, which is beneficial to the interfacial bonding strength. The Cu/Al LMCs fabricated by EP-UAM exhibited an obviously higher tensile strength and total elongation than those by PH-UAM. Such improvements in mechanical properties are mainly ascribed to (i) the higher strength retained for Cu and Al layers, (ii) the cooperative deformation of Cu/Al and (iii) back stress strengthening due to the formation of Cu atoms Guinier-Preston (GP) zones within Al matrix.