The influence of Al3Zr dispersoids on the recrystallization of hot-deformed AA 7010 alloys

The recrystallization of AA 7010 alloys (Al-6 pet Zn-2.4 pet Mg-1.6 pet Cu- Zr) during solution treatment is investigated as a function of Zr content a fter deformation under conditions simulating hot rolling. The respective ro les of the volume fraction and size of Al3Zr dispersoids are characterized by additions of 0.05 to 0.12 pet Zr and suitable heat treatments. Plane str ain compression (channel-die) tests at temperatures of 320 degreesC and 440 degreesC were conducted to strains of 1, and the samples subsequently solu tion-annealed at 470 degreesC. Recrystallization during this anneal was cha racterized by optical and electron microscopy and X-ray diffraction. The fr action recrystallized decreases with increasing Zr content, higher deformat ion temperature, and finer particle size. An original model based on the co ncept of the recrystallizable volume fraction is presented to predict the d egree of recrystallization in materials characterized by spatially heteroge neous microstructures.