Interface effects on the fracture mechanism of a high toughness aluminum composite laminate

The microstructure and the mechanical properties of a multilayer composite laminate based on aluminum 7075 and 2024 alloys produced by hot roll-bonding were examined. The composite laminate has been tested at room temperature under impact Charpy tests, three-point bend tests and shear tests on the interfaces. The toughness of the post-rolling tempered and T6 treated composite laminate, measured by impact absorbed energy in the crack arrester orientation, was more than twenty times higher than that of the monolithic Al 7075 alloy and seven times higher than that of Al 2024 alloy. The outstanding toughness increase of the composite laminate in the post-rolling tempered and T6 treated condition is mainly due to the mechanism of “interface predelamination”. By this fracture mechanism the interfaces are debonded before the main crack reaches them, warranting delamination in all interfaces. Therefore, delamination and crack renucleation in every layer are responsible for the improvement in toughness.Financial support from CICYT (Project MAT2003-01172) is gratefully acknowledged. C.M. Cepeda-Jiménez and J.M. García-Infanta thank the Spanish Ministry of Education and Science for a Juan de la Cierva contract and a FPI fellowship respectively. We also thank L. del Real-Alarcón for the welding work, F.F. González-Rodríguez for assistance during hot rolling and J. Chao-Hermida for assistance with the Charpy impact test.Peer reviewe