Advances in Mg/Al laminated metal composites via introducing interlayers: Mechanisms, strategies, and prospects

Mg/Al laminated metal composites (LMCs) are promising materials due to their low weight, high specific strength, and good formability, making them suitable for applications in automotive, aerospace, marine, and other industries. However, the significant differences in properties and coordinated deformation ability between Mg and Al alloys present serious challenges to the fabrication of Mg/Al LMCs. The interface is critical in determining the mechanical properties of Mg/Al composites, as it governs load transfer and metal bonding. Yet direct bonding often leads to the formation of brittle intermetallic compounds (IMCs) at the interface, which significantly reduce the interfacial bonding strength and consequently cause brittle fracture of the LMCs. Introducing an interlayer at the Mg/Al bonding interface can effectively mitigate or prevent the formation of brittle Mg-Al IMCs, providing a promising approach to improve the interfacial properties of Mg/Al LMCs and to develop lightweight LMCs with excellent performance. This review explores the intrinsic relationship between fabrication methods and interfacial bonding, provides a detailed analysis of the interfacial bonding mechanism, and discusses the design of interlayers from both thermodynamics and diffusion kinetics. Subsequently, the effects of different interlayers on the microstructure and mechanical properties of Mg/Al LMCs are analyzed, and the essential role of various interlayers in interface modification is thoroughly examined. Modifying the interfacial reaction products is the core objective of interface modification through the addition of metallic interlayers. In addition, different interlayers also induce changes in the microstructure of the interfacial bonding zone, and such microstructural changes are highly dependent on the fabrication process. Ceramic particles primarily act as a barrier preventing direct contact between Mg and Al, while also providing particle strengthening in the bonding zone. This work provides valuable insights for understanding and designing the failure mechanisms of Mg/Al LMCs incorporating interlayers.