Effects of homogenization on precipitation of Al3(Er,Zr) particles and recrystallization behavior in a new type Al-Zn-Mg-Er-Zr alloy

The effects of homogenization treatments on the precipitation behavior of Al3(Er,Zr) particles and theirs effects on recrystallization resistance in a new type Al-Zn-Mg-Er-Zr alloy have been investigated. Four different homogenization treatments, conventional one-stage homogenization, double-stage homogenization and ramp heating homogenization are carried out. Compared with that in the conventional one-stage homogenization, a finer particle size, higher number density and volume fraction of Al3(Er,Zr) particles can be obtained in other three homogenization treatments. In addition, the double-stage homogenization and the ramp heating homogenization can improve the Al3(Er,Zr) particles distribution and minimize the width of precipitation free zone in the region near the grain boundary, and provide an additional but nonnegligible strengthening effect for the Al-Zn-Mg-Er-Zr alloy. The difference in precipitation behavior of Al3(Er,Zr) particles lead to different recrystallization resistance. The high recrystallization resistance can be attributed to the larger fV/r ratio of Al3(Er,Zr) particles, which resulting in a higher Zener drag to effectively resist the recrystallization in Al-Zn-Mg-Er-Zr alloy during hot deformation and the subsequent thermal processing. Therefore, under the same annealing time, the double-stage homogenized and the ramp heating homogenized samples can achieve a significant lower recrystallized fraction compared with the conventional one-stage homogenized samples.