Deformation behavior and microstructure formation mechanism at the interface of Mg/Al composite plate during vibration assisted rolling process

Abstract

The poor metal mobility and insufficient fragmentation of the oxide film and hardened layer, which caused by low misalignment rate of the interface in traditional rolling (TR) process, lead to challenges to improve the interfacial bonding strength of Mg/Al composite plates. In this paper, a novel technology for manufacturing Mg/Al composite plates with excellent interfacial bonding quality by vibration assisted rolling (VAR) technology was proposed. VAR technology achieves high interfacial bonding quality of Mg/Al composite plates by introducing active shear stress through the misalignment of rollers. As a result, the interfacial bonding strength significantly increased from 28.5 MPa to 46.7 MPa, displaying an obvious improvement of over 64%. VAR technology enhances the degree of microstructures evolution and promotes the interdiffusion of elements in Mg/Al composite plates due to the frictional heat by the periodic misalignment of the rollers. Moreover, it promotes the multi-directional cracking of the hardened layer, and the cracking changes from strip cracking to cross cracking. It was attributed to the stress state of the Mg/Al composite plates change from biaxial compressive stress to state where biaxial tensile and compressive stress alternate periodically. In addition, the original shear stress in the rolling direction (RD) was increased and introducing an additional tangential direction (TD) shear stress at the interface. The technology could be beneficial for manufacturing Mg/Al composite plates with high interfacial bonding quality as well as provide a new technique for other metal composite plates.