7xxx aluminum alloys use zinc as the main alloy element, which can be strengthened by the heat treatment. Al-Zn-Mg-Cu alloy is developed by adding copper on the basis of Al-Zn-Mg alloy. Its strength is higher than that of 2xxxx aluminum. It is generally called ultra-high-strength aluminum alloy. It is widely used in aviation and aerospace fields, and becomes one of the most important structural materials in this field.