Segregation in irradiated alloys: The inverse Kirkendall effect and the effect of constitution on void swelling

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Abstract
The phenomenon of segregation of major alloy constituents under irradiation is considered. The available evidence on segregation of nickel to sinks in Fe-Cr-Ni alloys is reviewed, and some new data presented. The theory of the Kirkendall effect is extended to include the effect of superimposed vacancy gradients in binary alloys and applied to the case of an irradiated metal. It is found that if the effect of the interstitial flux is neutral, then solute segregation can occur at sinks because of differences in the vacancy diffusion coefficients of the alloy constituents. The theory predicts that slow-diffusing solutes will be enriched at sinks, as observed in Fe-Cr-Ni alloys. It is pointed out that one consequence of segregation is that an extra vacancy flux (the 'Kirkendall flux') is induced, which opposes the radiation induced flux to the sink. The consequences of this for void nucleation and growth are discussed.