Generating microstructures with specified correlation functions

A stochastic optimization technique has recently been developed that can re construct or construct random heterogeneous materials with specified statis tical correlation functions. We demonstrate how this technique can be used to reconstruct a digitized image of an interpenetrating, isotropic ceramic- metal composite. In this case, the two-point probability function displays no short-range order and the image is reconstructed by optimizing in two or thogonal directions only. However, this technique results in artificial ani sotropy in the unoptimized directions when one (re)constructs an image in w hich the isotropic two-point probability function exhibits appreciable shor t-range order. We show that by optimizing in more than two directions, one can effectively eliminate the artificial anisotropic effects for a system p ossessing significant short-range order. This is done by optimizing in thre e directions on a hexagonal grid and by optimizing in four directions on a square grid. Finally, an aspect of the nonuniqueness of the resulting struc tures is quantitatively examined. (C) 2001 American Institute of Physics.