Improved solution treatment for an as-rolled Al-Zn-Mg-Cu alloy. Part II. Microstructure and mechanical properties

► η particles can be completely dissolved after 5 min at 475 °C, whereas the dissolution of S particles is relatively difficult. ► The improved solution treatment can dissolve all the soluble particles with the recrystallised fraction less than 50%. ► The improved solution treatment can improve the mechanical properties of alloy AA7150 after retrogression and reageing.