Conductivity of Polycrystals

Abstract
The problem of the prediction of the effective electric or thermal conductivity of a polycrystal in terms of the conductivities of the constituting single crystals is treated by a variational method. It is assumed that the crystals are all of the same kind and randomly oriented. Consequently, the polycrystal is assumed to be homogeneous and isotropic in the large. However, no assumptions about the shape of the crystals have to be introduced.