Achieving high impact toughness through configuration design of 7xxx series aluminum alloy laminates

Laminated structures offer an effective strategy for producing impact-resistant metallic materials by significantly enhancing damage tolerance. However, research on how to design configurations for optimal impact performance remains limited. In this study, AB and ABAB configured laminates were fabricated from soft 7A52 (A) and hard 7A62 (B) aluminium alloys via hot-rolling, employing a rational combination of soft and hard layers. Charpy impact tests revealed that, owing to interfacial effects, the impact toughness in the normal direction (ND) was 2∼6 times that in the transverse direction (TD). The ABAB laminate exhibited toughness 2.7 times that of the AB laminate and 3.3 times that of the homogeneous 7A62 plate in the ND. Fractography and crack path analyses indicated that fracture behaviour is governed by morphological differences between layers, with crack deflection and pronounced delamination observed in the ABAB laminate. Microstructural characterization showed that coordinated deformation near interfaces during ND impact induced a geometrically necessary dislocation (GND) density gradient, leading to additional toughening. A distinct plastic zone at secondary crack tips further contributed to the enhanced impact toughness. This study not only clarifies the dependence of the toughening mechanism on the interface in laminates, but also proposes an effective approach for designing damage-resistant metallic materials subjected to impact loading.