Microstructure and mechanical properties of Mg/Al laminated composite: The effect of transition layer thickness

This study successfully prepared Mg/Al laminated composites with various thicknesses of pure Cu transition layer via extrusion, overcoming the challenge of forming of Mg/Al composite plates through stacked extrusion technology. The effects of varying Cu layer thicknesses on the microstructure, mechanical properties, and fracture behaviors were systematically investigated. Microstructure analysis showed an uneven Cu layer distribution at the interface of the composite plate, characterized by alternating thicker and thinner layers, which stemmed from the low fluidity of pure Cu during extrusion. Although the thicker Cu layer significantly inhibited the diffusion of Mg and Al elements, there was still a significant enrichment of Mg-Al intermetallic compounds (IMCs) in the thinner Cu layer. There hard and brittle IMCs caused cracking during the deformation process. Increasing Cu layer thickness did not significantly affect the microstructure but contributed to the decrease of strength owing to increased stress concentration. Moreover, the thicker Cu layer exacerbated its uneven distribution and Mg-Al IMCs enrichment at the interface, resulting in a pattern of first decreasing and then increasing elongation and shear strength of the laminated composite.