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The 7XXX aluminum alloys having a microstructure with precipitate free zones (PFZ) nearby the grain boundary, have received a great deal of attention due to their high strength, light mass, and yet poor fracture toughness. Experimental investigation into the effect of microstructure on the ductility was well established and comprehensive in the literature. A micromechanical model using a unit cell including some voids and relevant microstructural features was created. The competition between intergranular and intragranular fracture was investigated by comparing the void growth velocity between PFZ and matrix. The effects of void aspect ratio, relative PFZ volume, orientation of PFZ on the ductility of 7XXX aluminum alloys were analyzed. The results show that the model can explain the effect of microstructure on the competition between intergranular and intragranular fracture.
The 7XXX aluminum alloys having a microstructure with precipitate free zones (PFZ) nearby the grain boundary, have received a great deal of attention due to to their high strength, light mass, and yet poor fracture toughness. Experimental investigation into the effect of microstructure on the ductility was well established and comprehensive in the literature. A micromechanical model using a unit cell including some voids and relevant microstructural features was created. The competition between intergranular and intragranular fracture was investigated by comparing the void growth velocity between PFZ and matrix. The effects of void aspect ratio, relative PFZ volume, orientation of PFZ on the ductility of 7XXX aluminum alloys were analyzed. The results show that the model can explain the effect of microstructure on the competition between intergranular and intragranular fracture.