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 after deformation under conditions simulating hot rolling. The respective roles 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 strain compression (channel-die) tests at temperatures of 320 degreesC and 440 degreesC were conducted to strains of 1, and the samples subsequently solution-annealed at 470 degreesC. Recrystallization during this anneal was characterized by optical and electron microscopy and X-ray diffraction. The fraction recrystallized decreases with increasing Zr content, higher deformation temperature, and finer particle size. An original model based on the concept of the recrystallizable volume fraction is presented to predict the degree of recrystallization in materials characterized by spatially heterogeneous microstructures.