Effect of Number of Variants of Zirconium Hydride on Grain Growth of Zirconium

The microstructure characteristics of Zr-hydride in Zr are important concerns in metallurgy and nuclear engineering. In particular, it is known that the correlation between hydride and the grain boundary microstructure has a great influence on properties. In this study, a phase-field model was used to evaluate evolutions of the fractions of intra-granular and inter-granular hydride and multi-contacted hydride according to the number of structural variants of delta-hydride in the 3D system. The effect of the numbers of crystallographic variants of hydride on grain growth kinetics was also analyzed. We found that the pinning effect in 3D is minimized when hydrides have one crystallographic variant, which is contradictory observation with the 2D case. With grain structures with comparable average grain radii and quantities, we found that the fraction of the intra-granular and inter-granular hydrides increase as the number of crystallographic variants increases.