Microstructure and Mechanical Properties of the Spray-Deposited Al-10.8Zn-2.8Mg-1.9Cu Alloy at Various Aging Conditions

In this paper, Al-10.8Zn-2.8Mg-1.9Cu alloy was synthesized by the spray atomization and deposition technique. The microstructure and mechanical properties of the spray deposited alloy at various aging conditions (T6, T73 and RRA treatment) were studied using high-resolution electron microscopy, selected area diffraction, and tensile tests. The results indicate that the two types of GP zones, GPI and GPII zones are major precipitates for the alloy under peak-aged condition. The peak UTS and YS values achieved at an ageing temperature of 120 °C was 818 MPa and 793 MPa. Under two-step aging condition, the GP zones and η’ are major precipitates for the alloy, the discontinuous grain boundary precipitates are favorable to SCC resistance in over-aged condition, which reduces its strength 58 MPa(about 7%) comparing to the peak-aged condition. RRA treatment decreased ultimate tensile strength 25 MPa (about 3%) in values compared with the alloy at T6 condition.