Impact of domain anisotropy on CTE of isotropic microcrystalline material

An analytical, phenomenology-based model is proposed for thermal expansion of isotropic single-phase polycrystalline materials. Standard rules of mixing fail to predict correctly the coefficient of thermal expansion (CTE) of such materials. The model introduced in this paper explains and accurately reproduces the U-shaped thermal expansion curve of low-CTE ceramics ( cordierite and beta-eucryptite) quantitatively. The integrity function of a material is introduced as a measure of microcracking as a function of temperature. This function can be useful for analysis of different bulk properties of isotropic polycrystalline materials that depend on domain microcracking.