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.