Modeling of fluctuating interaction energy between a gliding interstitial cluster and solute atoms in random binary alloys

摘要

Fluctuation in microscopic distribution of solute atoms will act as a barrier for glide motion (i.e. 1D migration) of interstitial clusters in random alloys. We proposed an analytical model in which the total interaction energy between an interstitial cluster and solute atoms is a superposition of the interaction potential between the cluster and individual solute atom. Then we examined the nature of fluctuation in the total interaction energy of a gliding cluster. The average amplitude of the fluctuation was directly proportional to the square root of both the solute concentration c_s and the cluster radius r_c. The distance separating local peaks in the fluctuation was virtually independent of c_s and r_c, but showed dependence only on the range of the interaction potential. We proposed a model for another fluctuation in the interaction energy because of solute-solute interaction that is effective at high c_s. The models interpreted the results of the molecular statics simulations of the fluctuating interaction energy for interstitial clusters (7i, 61i and 217i) in dilute and concentrated Fe- Cu alloys with random solute distribution. We proposed that the fluctuation in the interaction energy is responsible for the short-range 1D migration that is observed in various alloys in electron irradiation experiments. The distance between local peaks would give the characteristic length of 1D migration in concentrated alloys.