The influences of Cr on dispersed phase and properties of Al-Zn-Mg-Cu-Zr alloys were investigated by mechanical testing, slow strain rate stress corrosion, intergranular corrosion, combined with optical microscope, scanning electronic microscope, transmission electronic microscopy (OM, SEM, TEM). Research shows that: with the increase of element Cr, the recrystallization and grain growth had been inhibited, the strength, toughness and corrosion resistance of the alloy increased first and then decreased; when added 0.1 wt% Cr element, the properties of the alloy are the best. The main reasons of that were as below: when added 0.1 wt% Cr element, (Al,Cr)3(Zr,Yb) appeared, that cohered with the matrix. When added 0.18 wt% Cr element, (Al,Cr)3(Zr,Yb) and Al18Mg3Cr2 had been found, making adverse effects on alloys. This work studied the effect of Cr content on recrystallization and grain growth in order to get a new super high strength aluminum alloy.
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