Effect of thickness ratio on interfacial structure and mechanical properties of Mg/Al composite plates in differential temperature asymmetrical rolling

Mg/Al composite plates with different thickness ratios were prepared by different temperature asymmetrical rolling + isothermal symmetrical rolling. The effects of different thickness ratios of component metals on microstructure, interface structure, and mechanical properties of composite plates were studied. It was found that the thickness of blocky intermediate compounds β(Mg₂Al₃) and γ(Mg₁₇Al₁₂) formed in the second pass rolling is inversely proportional to the component metal thickness ratio, and the maximum thickness of metallurgical bonding layer reaches 7.8 μm when the thickness ratio is 2. The main grains in matrix and clad plates are equiaxed grains and deformed grains, respectively. With the increase of thickness ratio, recrystallization of Mg layer increases first and then decreases, while Al side increases gradually because of the difference reduction of component metals. Due to the fine grain strengthening of matrix, the dislocation strengthening and low texture of clad plate, and the proper thickness of intermediate compounds, composite plate with a thickness ratio of 3 has the best mechanical properties. Its ultimate tensile strength and yield strength are 277.4 MPa and 253.9 MPa, respectively. Its elongation is the highest, up to 18.7%.