An important problem of radiation resistance of structural materials for reactors (different types of steels, including steels doping by low radio-active elements) was their phase stability under neutron irradiation which was associated with the formation of solute radiation-induced segregation near to grain boundaries. The diffusion of alloying elements under irradiation due to interstitial and vacancy diffusion mechanisms towards grain boundaries, which were perfect sinks for point defects resulted in the radiation-induced segregation formation near grain boundaries. Each grain boundary has the effective elastic stress field produced by the microstructure of grain boundaries. This elastic field could affect the formation of radiation-induced segregation in the dependence on an irradiation dose due to accumulation of impurity elements, gas atoms (He), formation on grain boundary He bubbles and precipitates especially at high doses of irradiation. The precipitates and over-pressurised He bubbles were the sources of internal stress fields too and they could dramatically change the effective stress field near grain boundaries. It will result in the redistribution of alloying elements near grain boundaries due to the additional diffusion driving force which was determined by the interaction energy of point defects with effective stress field near grain boundary.

Effect of Elastic Stress Field near Grain Boundaries on the Radiation Induced Segregation in Binary Alloys. M.V.Sorokin, A.I.Ryazanov: Journal of Nuclear Materials, 2006, 357[1-3], 82-7