Coordinated Regulation of Bonding Interfacial Structure and Mechanical Properties of Al/Mg Alloy Composite Plates by Electrically Assisted Rolling

Abstract Current research on the fabrication of rolled composite plates primarily focuses on processing and bonding mechanisms. Compared with hot-rolling technology, the electrically assisted rolling process has demonstrated excellent performance in interfacial bonding effects. However, the influence of different current loading modes on the interfacial recombination process of composite panels varies significantly. In this study, low-frequency electrically assisted rolling was used in the first pass to pre-bond a composite plate at a low reduction rate of 15%. High-frequency electrically assisted rolling was used during the second pass, and Al/Mg alloy composite plates were obtained. The interfacial microstructure and mechanical properties of the composite plate were coordinated regulation by designing the rolling reduction rate. The results showed the interfacial morphology of the alternating distribution of the melt-diffusion layer, diffusion layer, and the formation of a new Al/Mg bonding interface. At the melt-diffusion interface, the irregular intermetallic compounds (IMCs) and the new Al/Mg bonding interface were alternately distributed, and the IMCs contained the α-Mg, Mg17Al12, and Mg2Al3 phases. In addition, an extremely high shear strength of 78.26 MPa was achieved. Adhesion of the Mg alloy matrix was observed on the fracture surface of the Al alloy side. The high shear strength was mainly attributed to the formation of a unique interfacial structure and the appearance of a melt-diffusion layer. Compared to the diffusion-reduction interface, the regular rectangular IMCs and the new Al/Mg bonding interface were alternately distributed, and the IMCs consisted of the Mg17Al12 and Mg2Al3 phases. The shear test results showed that the shear strength of the interface reached 68.69 MPa, and a regular distribution of the Mg alloy matrix with dimples and the Al alloy matrix with a necking zone was observed on the fracture surface of the Al side. Tensile strength test results revealed a maximum value of 316.86 MPa for the Al/Mg alloy composite plate. The tensile and interfacial bonding strengths can be synchronously enhanced by coordinating the regulation of the interfacial structure. This study proposes a new electrically assisted rolling technology that is useful for the fabrication of composite plates with excellent mechanical properties.