3D-characterisation of microstructure evolution during annealing of a deformed aluminum single crystal

The microstructure within a 3D volume of a deformed Al single crystal is studied by a novel diffraction method before and after annealing for 5 min at 300 °C. The 99.996% pure single crystal of the S-orientation was channel die deformed to a strain of ϵ=1.5, producing a cell-block structure with distances of about 1 μm between dislocation boundaries.

By means of micro-focused hard X-rays from a synchrotron the orientations within a volume of 0.2×0.2×2 mm3 were mapped non-destructively. Cells or cell-blocks with orientations far from those of the principal poles can be identified individually with a resolving limit of 0.6 μm. The diffraction pattern related to these parts of the orientation distribution show little correlation between the as-deformed and annealed states.

They indicate the emergence of recovered cells and/or nuclei with orientations not present in the deformed state.