The application of orientation microscopy (OM) in TEM to study deformation microstructures provides essential information about the grains, sub-grains, boundaries and local crystallographic lattice deformation in a scale down to several nanometres. The comparison of microstructures in pure aluminium (4N) and aluminium alloy 6013, reversibly cold rolled up to 90 % is presented. Both microstructures are built of elongated grains and sub-grains in the rolling direction (RD) which lie nearly parallel to the sheet, which makes them morphologically similar. Significant differences became evident when comparing the measured orientation topographies: In the pure metal, layers thicker than 10 μm of similarly oriented sub-grains were observed, even for the deformation of 90 %. These layers were composed of bands or clusters of elongated sub-grains in the RD. Due to the presence across some of them of relatively small (1 - 10°), but cumulating, disorientation angles, they have been identified as transition bands. The alternation of orientation patterns was also recognized. The high frequency of the low angle grain boundaries (LAGB) inside the band indicates a well-developed sub-grain structure. The crystallographic orientation characteristics of the alloy are quite different. The alloy matrix consisted of well-developed high angle grain boundaries (HAGBs). The distances between them along the normal direction (ND) were much smaller than those in the pure metal and never exceed a few hundreds of nanometres. LAGBs in the elongated thin matrix grains were less ordered and created a less-expanded sub-grain structure. In this paper is presented qualitative and quantitative comparison of both microstructures and their influence on the mechanical properties and re-crystallisation behaviour. The use of OM in TEM, especially for investigation of small crystallographic orientation changes is shown.
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