Convection-induced compositional patterning at grain boundaries in irradiated alloys

Abstract

We consider the stability of precipitates formed at grain boundaries (GBs) by radiation-induced segregation in dilute alloys subjected to irradiation. The effects of grain size and misorientation of symmetric-tilt GBs are quantified using phase field modeling. A novel regime is identified where, at long times, GBs are decorated by precipitate patterns that resist coarsening. Maps of the diffusional P\'eclet number indicate that arrested coarsening takes place when solute advection dominates over thermal diffusion right up to the precipitate/matrix interface, overwhelming capillary effects. This contrasts with liquid-solid mixtures where convection only accelerates coarsening.