Effect of thickness ratio on microstructure evolution and coordinated behavior of Mg/Al composite plates in one-pass asymmetric rolling with differential temperature rolls

Abstract

To explore how varying matrix thicknesses influence interfacial morphology, microstructure, and mechanical properties of Mg/Al composite plates, this study prepared composite plates with distinct thickness ratios using an asymmetric rolling process featuring differential temperature rolls. The findings indicate that the Mg alloy largely exhibits significant recrystallization and sub-grained, while the Al alloy largely demonstrates a sub-grained characteristic. Notably, there exists a strong positive correlation between bonding strength at the interface and thickness ratio. As the thickness ratio increases, enhanced shear deformation at the interface triggers more slip system initiation, resulting in a gradual reduction of texture intensity in both the Mg and Al layers. Specifically, when the AZ31B/Al6061 thickness ratio reaches 5, the recrystallization level of the Mg layer is relatively elevated, accompanied by a fine and uniform grain size in the Al layer. This situation decreases the likelihood of stress concentration at the interface, which results in exhibiting relatively optimal elongation and bonding strength.