PROPERTIES OF Al-Zn-Mg-Cu ALLOY WHEN MODIFIED BY La, Ce, AND THERMAL-MECHANICAL

The influence of La, Ce elements and thermal-mechanical treatment on microstructure and mechanical properties of Al-Zn-Mg-Cu alloy are presented in this study. According to the results, when the alloy was added to the La, Ce elements, after casting, the grain size of samples was around 40-50µm compared to that of without about 65µm; and then these impurity samples attained 30µm after homogeneous mixture the grain sizes. After the cold deformation process, the distance between plates is 10µm. This homogenization process contributes to increasing the ductility of the studied alloy. In addition, the EDS lines study shows that after the combination of the deformation and heat treatment, the uniformation of elements mainly focuses on the boundary and in the grain. After recrystallization annealing, the grain size is around 10 µm with the modification sample. Further, as a result of ability deformation from the tensile test, these results demonstrate that the tensile test obtained 140 % when adding La, Ce contents into the alloy combined with thermal-mechanical treatment. The combined use of La; Ce and thermal-mechanical treatment have increased the ductility of Al-Zn-Mg-Cu alloy. The combination of modification and thermal-mechanical treatment has created a small grain size for the studied alloy.