Effect of of Yb, Cr and Zr additions on recrystallization and corrosion resistance of Al–Zn–Mg–Cu alloys

The effect of complex additions of Yb, Cr and Zr on recrystallization and corrosion resistance of Al–Zn–Mg–Cu alloy has been investigated. By complex additions of Yb, Cr and Zr to Al–Zn–Mg–Cu alloy, 20–50 nm dispersoids were formed in Al matrix and identified by X-ray diffraction analysis and energy dispersive X-ray spectroscopy as Zn, Mg, Cu, Zr-containing YbCr2A120 with cubic CeCr2Al20 crystal structure. The dispersoids remarkably inhibited the recrystallization of Al matrix, and a lot of low angle grain boundary of the Al–Zn–Mg–Cu alloy by complex additions of Zr, Cr and Yb investigated by electron back scattered diffraction was retained. Complex additions of Yb, Cr and Zr to Al–Zn–Mg–Cu alloy remarkably enhanced resistance to stress corrosion cracking (KISCC) from 9.8 to 17.0 MPa m1/2, exfoliation corrosion from EB+ to EA and intergranular corrosion with the improved strength, fracture toughness and ductility.