Study on the effects of microstructures on the fracture behavior of an Al-Cu-Mg alloy

In this study, a special fracture delamination in L-T fracture toughness specimens of an Al-Cu-Mg alloy was researched by applying three-dimensional optical microscopy (OM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD) methods. The results indicate that the fracture delamination is contributed by the cracks extending a long distance in the T-direction and extending internally along the L-direction, which can result in a lower fracture toughness value. The fracture delamination is determined by the level of grain flattening and the distribution of the second phases. The flat grains result in a tendency for cracks to extend in the T-direction. At the same time, the unevenly distributed Al 2 Cu and Al 2 CuMg phases lead to cracks extending in the L-direction, which eventually causes the formation of delamination fractures. The reduction in grain size can also contribute to weakening the fracture delamination to a certain extent.