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

Abstract

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 and the cluster radius . The distance separating local peaks in the fluctuation was virtually independent of and , 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 . 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.

Keywords:

• radiation damage
• point defect
• dislocation loop
• crowdion
• one-dimensional migration
• solution hardening

Acknowledgements

This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan (No. 21560868). A part of the numerical simulation was performed using the Center for Computational Materials Science, Institute for Materials Research, Tohoku University (Proposal No. 12S0408).