Optimizing mechanical property of spray formed Al-Zn-Mg-Cu alloy by combination of homogenization and warm-rolling

Abstract

Effect of homogenization and warm-rolling on the mechanical properties of Al-11.38Zn-2.45Mg-1.1Cu-0.13Zr-0.1Fe (wt. %) alloy fabricated by spray forming technology was studied by scanning electron microscopy (SEM), electron back-scatter diffraction (EBSD), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). The results indicate that the combination of homogenization and warm-rolling exhibit significantly potential for increasing the mechanical properties of the spray formed alloy. The introduction of two-step homogenization process can promote the precipitation of substantial amount of Al3Zr dispersoids, which provide the Orowan strengthening and inhibit recrystallization of the alloy. The warm-rolling at 200 °C produces a large number of dislocations, which not only provide strain hardening, but also promote the precipitation of η’ phase during aging treatment. Besides, the relatively low temperature rolling combined with Al3Zr dispersoids can avoid dynamic recrystallization and thus maintain fibrous microstructure of the alloy. An ultrahigh strength (YS = 868.9 ± 1.6 MPa, UTS = 878.6 ± 2.8 MPa, respectively) is achieved for the alloy due to synergistic effect of homogenization and warm-rolling.