Development of ultrafine grained Al–Zn–Mg–Cu alloy by equal channel angular pressing: microstructure, texture and mechanical properties

Abstract

In this article, an effort has been made to investigate the evolution of microstructure, texture and mechanical properties of AA 7075 alloy during equal channel angular pressing (ECAP) by route BC at room temperature at a pressing speed of 1 mm/min. Transmission electron microscopy (TEM) revealed the presence of rod-like (MgZn2) precipitates in annealed conditions which were broken after two ECAP passes along with remarkable grain refinement due to high imposed strain after the second pass. After two consecutive ECAP passes, hardness, yield strength, and tensile strength of the alloy increased significantly in comparison to initial annealed condition. The fraction of high angle boundaries (HABs) and grain misorientation angle significantly increased after ECAP passes compared to the initial condition. Texture measurements were performed by X-ray diffractometer (XRD), on TD plane (parallel to extrusion direction). Texture results revealed the dominance of Cθ and A2θ∗ components after the first pass and the presence of strong Bθ, B¯ θ and A¯ θ components along with weaker A2θ∗,Cθ components after the second pass. Scanning electron microscopy (SEM) revealed that the average dimple size was gradually reduced with increasing the ECAP passes.