Microstructural development of spray-deposited Al-Zn-Mg-Cu alloy during subsequent processing

In this study, Al-10.8Zn-2.8Mg-1.9Cu alloy was synthesized by the spray atomization and deposition technique. The structural characteristics of spray-deposited alloy and their development during subsequent hot extrusion and heat treatment were investigated by means of scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction. The results indicate that the microstructure of the alloy mainly is composed of the All matrix, the Mg(ZnCu)(2) compounds with various shape. The fragmentation of the Mg(ZnCu)(2) phases in the alloy has been regarded as one of the main feature during extrusion. After solution treating, the microstructure is found to be composed of the Al matrix and a spot of Al7Cu2 Fe particles. The GP zones and/or the metastable eta' phase from the matrix are major precipitates for the alloy under peak-aged condition (16 h at 120 degrees C). (C) 2008 Elsevier B.V. All rights reserved.