Microstructural study of Ce-Nd alloys

The present work is concerned with the grain structure and grain growth in some cerium-neodymium alloys. The grain size in a Ce-10 wt.% Nd alloy is determined by the rate of cooling through the two-phase γ + δ region. Grain growth in the upper γ-phase is a diffusion-controlled process with activation energy close to that associated with self-diffusion of cerium. In the course of spontaneous oxidation, epitaxial CeO₂ layers grow on the Ce-alloy surface. The presence of such layers has been previously observed on a variety of substrate materials but not on the parent metal cerium. As these layers become thicker, coherency strains give rise to a network of cracks that develop within the oxide layer. The coherence between the cerium-substrate and the oxide layer is maintained even across the initially formed intermediate sub-oxide layers.