Feasibility of dispersed phase grain refinement in ceramics.

Abstract

The feasibility of dispersed phase grain refinement in ceramics is assessed. Conditions for grain size stabilisation of normal grain growth are derived using a Zener type analysis for random dispersions and for the case in which all particles are located at specific sites upon a grain boundary. The calculations predict the relative stabilising effects of particles located at grain boundaries, triple—grain edges and four—grain corners. Other factors reviewed include the effects of particle size instability, nucleation of discontinuous grain growth, and possible methods for its prevention. It is concluded that dispersed phase grain refinement in ceramics is feasible. The general predictions are applied to the case of a BeO moderator and used to predict the most promising additives for further investigation.