Stress orientation of second-phase in alloys: Hydrides in zirconium alloys

A model for precipitation of the plate-shaped second-phase under applied stress is presented. The precipitates in the matrix-precipitate system are represented by their local volume fraction ζζ and an orientation parameter θθ that defines the alignment of a precipitate platelet in a given direction. Kinetic equations, based on diffusion theory and classical nucleation theory, are used to describe the time evolution of ζζ and θθ. The model is used to describe the stress orientation of hydrides in Zr-alloys in light of experiments.