Representations of Polycrystalline Microstructure by n-Point Correlation Tensors
An important class of representations of polycrystalline microstructure consists of the n-point correlation tensors. In this paper the representation theory of groups is applied to a consideration of symmetries in the n-point correlation tensors. Three sources of symmetry are included in the development: indicial symmetry in the coefficients of tensors, symmetry associated with the crystal lattice, and statistical symmetries in the microstructure induced by processing. The central problem discussed here is the residence space, or the space of minimum dimension occupied by correlation tensors possessing such symmetries. In addition to the general case of correlation tensors possessing such symmetries, a model microstructure is also considered which embodies an assumption of no spatial coherence of lattice orientation between neighboring grains or crystallites. It is shown that the model microstructure generally results in residence spaces of lower dimension.