Effects of Gd and Y additions on microstructure and properties of Al-Zn-Mg-Cu-Zr alloys

► The inhibition recrystallization effect is more obvious when adding complex Gd and Y. ► The micro-segregation of the Al-Zn-Mg-Cu-Zr alloy could be significantly reduced after adding Gd or both with Gd and Y. ► Adding single Gd or composite Gd and Y can both can accelerate the peak aging time, improve the peak hardness, and extend the duration of peak aging time. ► Compared with Al-Zn-Mg-Cu-Zr alloy, the alloys with Gd or with Gd and Y can significantly improve the strength and elongation of T6 state.