Preparation of magnesium-aluminum microlaminated composites: evaluation of process applicability and system properties

To overcome the limitations of traditional single-variable experiments, this study employs response surface methodology (RSM) with Box-Behnken design (BBD) to optimize key vacuum hot-pressing process parameters (plate thickness, holding time) for Mg/Al laminated composites, establishing quantitative relationships between parameters and mechanical properties. At Mg plate thickness of 0.5 mm, Al plate thickness of 0.1 mm, and 6h holding time, the composites show excellent specific bending strength (162 N·m/kg) and specific compressive strength (183 N·m/kg). Furthermore, combined with the Optimal (custom) design, the influence of structure composition on mechanical properties is revealed. The results show that the residual Mg layer has a positive regulation effect on the mechanical properties. Although the increase of the residual Al layer reduces the strength, it improves the plasticity. The regulation of intermetallic compounds on mechanical properties shows outstanding nonlinear characteristics. Fracture mechanism analysis reveals that cracks preferentially initiate in brittle intermetallic compounds during three-point bending, subsequently propagating along a ductile-brittle alternating path. The difference in the structural composition of the composites causes different combinations of fracture modes, mainly involving brittle phase fracture, interfacial delamination, ductile layer shear tearing and brittle phase induced interfacial debonding. Under compressive loading, the composites also exhibit mixed mode fracture, specifically manifesting as brittle fracture of intermetallic compounds, shear fracture of the Mg layer, and plastic instability failure of the Al layer. The process-structure-property correlation established and fracture mechanism revealed in this study hold significant implications for optimizing vacuum hot-pressing processes and designing high-performance Mg/Al laminated composites.