A high zinc content alloy of Al-11Zn-2.4Mg-2.1Cu-0.1Zr was fabricated

and effects of heat treatment such as quenching temperature

cryogenic treatment and aging on microstructure and mechanical properties of the alloys prepared were analyzed comparatively.The results reveal that the quenching cool rate and the solid solubility of supersaturated solid solution phase are increased obviously with the decrease of the quenching temperature

so the inducing force of aging phase transition is increased significantly

leading to the smaller size of precipitation strengthening phase

whereas the precipitation number and density of strengthening phase distributed in the grain and nearby the grain boundaries are increased greatly

resutting in the improvement of tensile strength.The mechanism of cryogenic treatment is mainly characteried by pre-aging

which is controlled evidently by the volume size of components.Comparing with the aging treatment at 135℃for 16 h

more GP zones andη’precipitation strengthening phases can be observed both in the grain and nearby the grain boundaries with aging treatment at 120℃for 24 h

where the average tensile strength

yield strength and elongation reach 716 MPa

702MPa and8.9%

respectively.