Research on process regulation and deformation mechanism of Mg/Al composite plates during hot bending forming

The bending forming of Mg/Al composite plates can effectively expand their application fields. In this study, the "heat treatment + hot bending" combined process significantly improved the bending forming performance of the Mg/Al composite plates prepared by rolling. The optimal process path for the synergistic interface bonding ability and bending forming performance was obtained by holding at 200 °C for 60 minutes immediately followed by isothermal bending. The microstructure evolution and deformation mechanism of the Mg/Al composite plates from preparation to forming application were systematically studied. It was found that the fracture of the magnesium-aluminum composite plates at room temperature showed a phased pattern: cracks initiate in the magnesium layer, deflect at the neutral layer, propagate laterally along the interface, and finally penetrate the aluminum layer. The deformation mechanism of the magnesium layer evolves across the plate thickness. Hot bending enhances plasticity by activating dynamic recrystallization in the inner magnesium layer and non-basal slip systems. Neutral layer shift during bending causes dynamic redistribution of stress and strain within the magnesium layer. The plasticity enhancement of the magnesium layer at the interface is attributed to the interlayer coordinated deformation mechanism at the interface. The magnesium layer is dominated by <a> slip along the basal plane and accompanied by <c+a> slip activation at the cone surface. Meanwhile, the aluminum layer strengthens the interface's cooperative deformation ability through forms such as dislocation proliferation and movement. These findings provide theoretical guidance for forming applications and process optimization of Mg/Al composite plates.