Study on strengthening and toughening mechanisms of Cu/Al composites dominated by interface layer

Cu/Al composites have the excellent properties of both Cu and Al, and have the properties of light weight and high conductivity, so they have been widely concerned. In this paper, 5-mm-thick Cu/Al composites prepared by the cast-rolling process are used as experimental materials. To reveal the strengthening and toughening mechanisms of the Cu/Al composites, the interfacial structure, micro-morphology, stress-strain condition, and GND distribution of Cu/Al composites before and after deformation were characterized utilizing TEM , TKD, and EBSD . The results show that the submicron intermetallic compounds Al 2 Cu and Al 4 Cu 9 are formed from the casting-rolling Cu/Al composites. After 15% tensile deformation , many gaps occurred in the interface layer , but at the gaps, there was no crack spreading to the Cu and Al layers. Meanwhile, the deformation in different directions occurs in the Cu grains near the interface, forming a dislocation wall, and the entanglement of the dislocation occurs in the Cu layer near the interface, which contributes to the improvement of tensile strength . The Al layer near the interface layer produces kink bands, which helps to improve the ductility of the composites. Besides, due to the action of the hard intermetallic compound layer, with the increase in tensile deformation, a large number of GND are gradually accumulated in the Cu and Al layers near the interface, resulting in remote back stress, which makes the softer Cu and Al layers obtain higher strength . At the same time, the back stress caused by GND will induce strain hardening, which helps to maintain ductility, so that Cu/Al composites have higher plastic deformation ability while improving mechanical properties. • The effect of the interfacial layer on the strengthening and toughening of Cu/Al composites during deformation was studied. • The Cu/Al composites could induce dislocation pile-up in the Cu side, after tensile deformation. • The deformation in different directions is generated in the Cu layer grain and the dislocation wall is formed. • GND accumulates gradually at the interface, with the progress of tensile deformation.