Orientation Dependent Recovery in Strongly Deformed Al-0.1%Mn Crystals

Abstract

Single crystals of Al-0.1%Mn have been channel-die compressed to a true strain of 2.3 and their recovery behaviour at 240-320°C investigated by microhardness measurements, EBSD microtexture mapping and X-ray line broadening analysis. The crystal orientations are the nominally stable Goss {110}, brass {110} and S {123}. For all three orientations the microhardness decreases with a logarithmic time dependency but the instantaneous recovery rates of the Brass oriented crystals are systematically lower than those of the other two orientations by a factor of about 2. The dislocation densities decrease rapidly in the first stages of recovery (<1 min) by dislocation dipole annihilation and more slowly thereafter. In the Goss and S orientations the later stage of recovery is due to sub-grain growth. The orientation dependency is ascribed to the relatively low misorientations developed by plastic straining in the Brass crystals (average about 4°) compared with the Goss and S orientations (about 7-8°).