Orientation Correlation in Grain and Phase Boundaries

The properties of grain and phase boundaries depend on five angular coordinates, i.e. three parameters specifying the orientation difference across the boundary and two parameters specifying the orientation of the boundary normal direction in space or with respect to the crystal lattice. Hence, five-dimensional boundary distribution functions have to be considered. If one considers only misorientation a three-dimensionalmisorientation distribution function is obtained. The deviation of this function from the #8220;uncorrelated” misorientation distribution yields the orientation correlation function. The most economical representation of these functions is the one using series expansions in terms of symmetrized harmonic functions. With the present state of experimental technique it seems to be impossible to determine the complete boundary distribution functions. However, two-dimensional analoga of these functions can be obtained from electron diffraction measurements.