A radiation-induced segregation model for concentrated alloys, based upon the inverse Kirkendall effect, was used to predict element segregation in model alloys under irradiation conditions. In this model, segregation was the result of preferential atom-vacancy jumps. Under conditions of high irradiation flux, or wide temperature range, a description of interstitial migration had to be included in the model. The rate theory was used here to simulate radiation-induced segregation near to the grain boundary in Fe–Cr–Ni alloys. A model for diffusion, and for the conversion of a mixed interstitial dumb-bell, was used to describe the flux of interstitials. Six types of interstitial dumb-bell, and their conversion by a jump of one of its constituent atoms to a neighboring site to form a dumb-bell of differing orientation, were considered. The vacancy flux was described somewhat as in the Wiedersich–Okamoto–Lam model; assuming its migration via position exchange with a lattice atom.

Diffusion and Conversion of Interstitial Dumb-Bells in Segregated Ternary Alloys under Irradiation. O.Shepelyev, N.Sekimura, H.Abe: Journal of Nuclear Materials, 2004, 329-333[2], 1204-7