Experimental Investigation on Heat Treatment of Spray-Forming Ultrahigh Strength Al-Zn-Mg-Cu Alloys

The microstructures of as-deposited and extruded ultrahigh strength aluminum alloys by spray-forming were investigated. The aging-curves and tensile properties were tested after solid-solution treatment and aging treatment. The result shows that in as-deposited alloys, many porosities are obvious. In extruded alloys, however, there are large amount of Cu-rich particles. The solid-solution treatment temperature should not be higher than 490℃ because much of grain-boundaries melt in this temperature. At 120℃, the time to obtain hardness peaks ranges from 15 to 25 h. At 135℃, the relationship is obvious between the time and the composition of the alloys:The more Zn contented, the less the time; the tensile strength of the alloys keeps on about 700 MPa.