Irradiation of fcc austenitic alloys by neutrons or ions leads to the creation of large numbers of immobile Frank interstitial dislocation loops. While cluster dynamics modeling techniques work well to predict the microstructural evolution of bcc metals and alloys under irradiation, where many of the defects are mobile, they overpredict by orders of magnitude the number densities of Frank loops in fcc alloys compared to ion irradiation experiments. To address this over nucleation issue, I am working on a modification of the reaction-diffusion cluster dynamics model for a nickel-base austenitic alloy to incorporate a new reaction term addressing the effects of damage cascades overlapping with existing dislocation loops, which will activate after a certain “critical dose” where enough damage has occurred that the probability of cascade overlap becomes significant. To parameterize this reaction term, I am using molecular dynamics to simulate cascade overlap in nickel.
Email: smorri20@vols.utk.edu