Coupling effect of primary voids and secondary voids on the ductile fracture of heat-treatable aluminum alloys

Ductile fracture of commercial aluminum alloys is controlled not only by the primary voids but also by the secondary voids, which are respectively nucleated at cracked constituents and at decohered dispersoid. In this paper, experiment and modeling were carried out to study the combined effect of the two populations of voids on the ductile fracture in two kinds of heat-treatable aluminum alloys, i.e., Al–Cu–Mg alloys and Al–Mg–Si alloys. Different heat treatments were applied to the alloys to achieve various combinations of the two voids, which were subsequently related to the mechanical properties. A multiscale fracture model was proposed to describe quantitatively the relationships between parameters of the two voids and the ductility and fracture toughness of heat-treatable aluminum alloys. It is revealed experimentally and theoretically that the presence of secondary voids will reduce the ductile properties especially when the intervoid spacing is less than about 0.5 μm. All calculations are in good agreement with experimental results.

► We studied the combined effect of primary and secondary voids on the ductile fracture of aluminum alloys.
► Secondary voids will reduce the ductile properties especially when the intervoid spacing is less than about 0.5 μm.
► A multiscale fracture mode was proposed to quantitatively describe the coupling effect.