Orientation Correlations in Metal Structures from the Micrometer to Nanometer Range

Abstract

Distributions of boundary misorientations in aluminium are measured as a function of deformation for strains up to 10. These experimental distributions are compared to misorientation distributions generated from a random mix of orientations present in the microstructure. It is found that for all strains investigated, the experimental distributions contain a significant higher fraction of low angle boundaries than that expected from the theoretically calculated distributions assuming a random mixing of orientations. This means that there are clear correlations between neighbouring orientations in the microstructure even after strains as large as 10. A similar analysis is done for annealed samples. Here it is found that conventional recrystallisation of a low strained sample leads to almost similar experimental and calculated distributions i.e. almost no correlations exist between neighbouring grains, whereas annealing a sample deformed to e=10 leads to significant structural coarsening, but a large fraction of low angle boundaries are maintained in the experimental misorientation distribution, which is not seen in the theoretically calculated distribution.