Modeling of the microstructural behavior of hydrided zirconium alloys

Abstract

A multiphase microstructural system of two types of hydrides; f.c.c. δ and b.c.c.. e hydride precipitates within a parent h.c.p. zircaloy-4 parent matrix were modelled by a crystalline dislocation-density and a finite-element (FE) method that is specialized for large inelastic strains and nonlinear behavior. The different crystalline structure of the hydrides, the parent matrix, and the orientation relationships between the different crystalline phases have been accounted for and modeled with a validated FE approach. The effects of radial hydride factors, hydride volume fraction, hydride morphology, and hydride orientation and distribution on overall behavior were investigated. The predictions provide an understanding of why a distribution of circumferential hydrides have higher strength and ductility than a distribution of radial hydrides. Furthermore, zircaloy δ (f.c.c.) hydride systems have less ductility and strength than the zircaloy e (b.c.c.) systems.