Lamination has been shown to improve the fracture critical properties of both monolithic materials and composites. Interface delamination relaxes the stress concentration and spreads the deformation, which delays catastrophic failure and increases the Charpy impact energy. The tensile and impact properties of laminated composites depend on the interfacial strength. Bilayer laminates consisting of aluminium and aluminium composites were loaded in four-point bending. The bend bars were notched close to, but not onto, the interface. A ligament underneath the notch ranging from 0.1 mm to 0.5 mm to the interface was deliberately left in all the bend bars tested. The reasoning is that laminates can have defects or develop matrix cracks in real life situations at any location in the matrix, not necessarily at a place touching the interface. The laminates were bonded by different processes. One epoxy bonded and two types of diffusion bonded interfaces were tested. Two types of delamination have been identified : delamination without any extension of the primary crack and delamination after the extension of the primary crack into the interface. A commonly used model was employed to analyse the second mode of delamination, while a new model is proposed to predict the first type of delamination.