Fracture mechanisms assessment of a multilayer material with high strength and excellent impact toughness based on the aerospace Al 7075 alloy

An aluminium multilayer laminate has been processed by hot rolling. It is constituted by 19 alternated layers of high-strength aluminium alloy (Al 7075-T6, 82 % vol) and thinner pure aluminium layers (Al 1050-H24, 18 % vol). The microstructure of the constituent alloys and the composition gradient across the interfaces has been characterized. The multilayer laminate and the as-received aluminium alloys have been tested at room temperature by Vickers microhardness, three-point bend test and impact Charpy test. The outstanding improvement in damage tolerance, which is 18 times higher than that for the as-received Al 7075 alloy, is due to both intrinsic and extrinsic fracture mechanisms operating in the multilayer laminate during mechanical testing. (Author) 19 refs.