Crystallographic mechanism for crack propagation in the T7451 Al–Zn–Mg–Cu alloy

The electron back scattering diffraction (EBSD) technique has been applied in investigating the crystallographic mechanism of crack propagation in Al–Zn–Mg–Cu alloy. It is revealed that intergranular and transgranular crack propagation behaviours both exist and the relationship between crack propagation and orientations of adjacent grains complies with the crystal plastic deformation mechanism. When the interfacial angle between fracture surfaces of two adjacent grains is small, the crack propagates through grain boundaries with deflection of a certain angle; while small interfacial angles cannot form between slip planes in two adjacent grains, intergranular propagation occurs.