This article presents an asymmetric aluminum foam sandwich (AAFS) with a metallurgical bonding interface, fabricated by integrating the two‐step foaming with vacuum bonding using a Zn interlayer. The structure features an AlMg1SiCu face sheet and a dense, process‐generated bubble‐free layer, which eliminates the need for a second external panel. Optimal foaming at 595°C for 8 min yields equivalent thickness between the bubble‐free layer and the face sheet. Microstructural analysis reveals that the vacuum‐bonded interface, consisting of Zn–Al eutectic and eutectoid zones as well as oxide films, is transformed during secondary foaming. This transformation involves the homogenization of the initial structure, along with the migration and fragmentation of the oxide films, primarily driven by pore growth and Zn/Al interdiffusion. Consequently, a continuous metallurgical bond is established. The AAFS exhibits good compressive properties with a yield strength up to 23.17 MPa and an energy absorption capacity of 13.36 MJ/m 3 , validating the proposed manufacturing route.
Li et al. (Sat,) studied this question.