The modelling of combined radiation-induced and thermal non-equilibrium segregation of chromium in neutron-irradiated austenitic stainless steels

A model of the radiation-induced segregation (RIS) and thermal non-equilibrium segregation (TNES) at grain boundaries has been established within a phenomenological theory. This model indicates that the magnitude and extent of segregation is dependent upon the formation of solute-point defect complexes that migrate to grain boundaries. Theoretical predictions are made for the TNES and RIS of chromium in austenitic stainless steels for the first lime. The results indicate that for TNES, chromium creates a positive binding energy in the complex, and is thus enriched at the grain boundary. For RIS, chromium produces a negative binding energy in the complex, and is thus depleted at the grain boundary. The combined effect of the two segregation mechanisms is discussed in relation to the evolution of the segregation profile exhibited by the grain boundary. The segregation profiles are shown to be illustrative of analytically measured profiles for similarly treated materials.