Microstructural-based measurement of local stored energy variations in deformed metals

Three single crystals of typical fcc rolling texture orientations-{112} < 111 > (C), {123} < 634 > (S), and {110} < 112 > (B)-have been deformed by plane strain compression at room temperature, and the stored energy of deformation in each has been calculated from measurements in the transmission electron microscope (TEM) of dislocation boundary spacings and misorientation angles. The stored energy has been determined on two length scales: the single crystal scale and, for orientations in which localized glide bands (LGBs) are present, on the local length scale. On the crystal scale, it is found that the stored energy shows a strong dependence on the crystallographic orientation; the highest is for the C orientation and the lowest is for the B orientation. For the C and S orientations, where LGBs develop during deformation, the differences in stored energy between the LGB and matrix regions can be as large as the differences between the average values for each single crystal. The observed variation of stored energy on the crystal scale and the local scale can be related to the experimental observations of the flow stress and to the recrystallization behavior of the three crystal orientations.