The stored energy of plastic deformation has been estimated from transmission electron microscope measurements of dislocation boundary spacings and misorientation angles using Al (99.99 pct) cold rolled to reductions of 5 to 90 pct as an example system. In order to obtain the most accurate estimate of stored energy, it is necessary to take into account the presence of two classes of dislocation boundary, considering the boundary misorientation angle distribution and the stereology of each class independently. Stereological relationships are developed to predict the stored energy estimates that would result from electron backscatter pattern (EBSP) investigations on these microstructures. The calculations show that EBSP investigations can be used to estimate the stored energy, but that at low strains, the limited angular resolution will lead to a significant underestimation. A relationship between the flow stress (0.2 pct offset) and the stored energy is found, though the relationship differs significantly for the low and high strain regimes. At low strains, the flow stress is linearly related to the square root of the stored energy (E S ) according to Ϫ 0 ϭ M␣[(G/K)E S ] 0.5 , where G is the bulk modulus, M is the Taylor factor, and K and ␣ are constants.

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SummaryThe effect of several data collection and processing choices has been examined for high-resolution electron back-scatter pattern (EBSP) investigation of a highly deformed sample. The results were compared with a transmission electron microscope (TEM) investigation of the same sample. The estimated dislocation cell size was examined as a function of data cleaning strategy, line intercept vs. reconstruction method, critical misorientation angle definition and step-size. The best agreement with the TEM results was obtained using a modified relative reconstruction algorithm on fine step-size maps allowing some of the noise in the data to be overcome.Step sizes of up to one-quarter the average cell size yielded similar values for the estimated average cell size. As a result of the mixture of both high-and low-angle boundaries, single diffraction condition TEM images may give larger cell size estimates than the EBSP data. Orientation noise in the EBSP data, however, still limits the extent to which quantitative information can be extracted.

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