Study on the interfacial bonding mechanism and microstructure of large thickness ratio Al/Mg/Al laminated composites

Large-thickness-ratio (LTR) Al/Mg/Al laminated composites were fabricated by single-pass hot rolling with reduction ratios from 33% to 66%. The effects of reduction ratio on interfacial morphology, bonding quality, microstructural evolution, and mechanical properties were investigated. With increasing reduction, both Al and Mg layers thinned, while the Mg/Al thickness ratio peaked at 49%. Differential plastic flow induced wavy interfaces at higher reductions, and continuous, well-bonded interfaces were obtained at reductions ≥49%. Increasing reduction promoted grain fragmentation, shear-band formation, and dynamic recrystallization in the Mg core. Tensile strength varied slightly, whereas elongation was highly sensitive to reduction ratio, reaching a maximum of 26% at 49%. These results provide guidance for optimizing high-performance LTR Al/Mg/Al laminates.