Modeling the Radiation-Induced Segregation of Undersized Solutes Near Grain Boundaries

Abstract

A system of diffusion equations is formulated for component and point defect concentrations near grain boundary (GB) in irradiated ternary alloy, in which a minor component has a small atomic size. A possibility of GB migration is taken into account. It is assumed that undersized atoms migrate via interstitial mechanism as nearly stable mixed dumbbells. Radiation-induced segregation (RIS) of Si near both the motionless and moving GBs in Fe-Cr-Ni alloys is modeled by solving the system of equations. A competition between the undersized solute and the major alloy component which tends to segregate at GB is studied by varying the Ni content. It is shown, that the formation of strongly bounded mixed dumbbells consisting of the undersized alloying atom and one of the major component atom can significantly enhance RIS of alloying elements around point defect sinks.