Grain Boundary and Texture Evolution during Severe Plastic Deformation of Green Al Powder Compacts

Commercially pure green Al powder compacts were subjected to single-pass friction stir processing (FSP) with different tool rotational speeds. The effect of temperature and strain rate on the microstructural evolution during FSP was analyzed. The evolution of texture and different types of grain boundaries (GBs) (i.e., misorientation of GBs between 2 & DEG; to 5 & DEG;, 5 & DEG; to 15 & DEG;, 15 & DEG; to 40 & DEG; and 40 & DEG; to 65 & DEG;) were analyzed to find out the mechanism behind the microstructural evolution in the samples. At a lower strain rate, the restoration mechanism is mostly through extended recovery or continuous dynamic recrystallization. At a higher strain rate, with increased temperature, concomitant evolution of rotated cube component is noticed. Texture weakening with an increase in rotation speed and the presence of rotated cube component suggests the presence of other recrystallization mechanisms than continuous dynamic recrystallization.