Microstructure and mechanical properties of spray-deposited Al-Zn-Mg-Cu alloy processed through hot rolling and heat treatment

In this study, Al-10.8Zn-2.8Mg-1.9Cu alloy was synthesized by the spray atomization and deposition technique. Microstructure and mechanical properties of the spray-deposited alloy processed through hot rolling and heat treatment were investigated by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction and tensile test. The results indicate that the microstructure of the spray-deposited alloy is mainly composed of the Al matrix and the Mg(ZnCu)2 compounds. The fragmentation of the Mg(ZnCu)2 phases in the alloy has been regarded as one of the main feature during hot rolling. After solution treating, the microstructure is found to be composed of the Al matrix and a spot of Al7Cu2Fe, Al9FeNi compounds. The spray-deposited Al-Zn-Mg-Cu alloy in the T6 temper displays superior strength due to the presence of two types of coherent GP zones (spherical GPI zones and thin platelet GPII zones).