Elastic behaviour of orientation-correlated grains in multiphase aggregates

Abstract

Diffraction elastic constants (DECs) describe the elastic response of a subset of orientation-correlated grains which share a common lattice vector. DECs reflect the elastic behaviour of the single-crystal constituents through their dependence on grain orientation. DECs furthermore depend on the behaviour of the polycrystal aggregate both through the dependence on preferred orientation and through the average elastic interaction of the grains in the subset with their surroundings. The latter is also known as grain–matrix interaction which is grain-shape dependent. Both dependencies can make the DECs uniquely sensitive to the elastic effects of the grain shape, texture and phase composition. Several micro-mechanical models are explored for use in calculating both DECs and overall elastic constants. Furthermore, it is shown how discrete data from electron backscatter diffraction on grain shape, grain orientations and neighbouring grains can be used for DEC calculations. Lastly, the inverse problem of calculating single-crystal elastic constants from DECs is discussed in detail. All calculations discussed in this work can be verified using the freely available computer program IsoDEC.