Effect of Zr, Cr and Pr additions on microstructures and properties of ultra-high strength Al-Zn-Mg-Cu alloys

► Examined effects of Zr, Cr and Pr on microstructures and properties of ultra-high strength Al-Zn-Mg-Cu alloys. ► 10-20 nm coherent dispersoids of Zn, Mg, Cu, Cr, Pr-containing A13Zr with cubic L12 structure are formed by adding Zr, Cr and Pr to Al-Zn-Mg-Cu alloy. ► The dispersoids remarkably inhibited the recrystallization of Al matrix, and numerous fine subgrain boundaries were retained. ► Additions of Zr, Cr and Pr to Al-Zn-Mg-Cu alloy can improve the strength, ductility, fracture toughness and corrosion resistance.