Characterization of effects of heat treated anodized film on the properties of hygrothermally aged AA5083-based fiber-metal laminates

The present work studies the effects of annealing and anodizing an AA5083 sheet on the metal/composite laminate adhesion, mechanical properties and corrosion behavior of the seawater hygrothermal aged AA5083-carbon fiber/epoxy fiber-metal laminates (Al FMLs) for marine applications. The results reveal that annealing at 250 °C decreases the porosity and the pore size of the anodized film. Consequently, the mechanical properties of Al FML deteriorate and metal/composite laminate interface weakens. Moreover, the mechanical properties of AA5083 sheets and laminates deteriorate after hygrothermal ageing. The higher percentage decrease in the mechanical properties of the Al FML having non-annealed AA5083 layers compared to annealed AA5083 layers is due to the excessive corrosion of the non-annealed AA5083 layers. The anodized annealed AA5083 sheets show the least mass losses in the nitric acid mass loss test (NAMLT). The failure mechanism in non-aged Al FMLs is the fracture of the outer AA5083 and composite laminate layers, while in aged Al FMLs, metal/composite laminate and fiber/resin interfaces delaminate.