Abstract:
Clustering of irradiation produced point defects is recognized to impede dislo-
cation motion and hence influence mechanical-deformation characteristics. In this paper,
a model is presented for the simultaneous nucleation and growth of vacancy and interstitial
loops in irradiated metals. The model is based on the homogeneous time-dependent rate
cheery. Conservation equations are developed for single defects as well as defect cluste-s.
Defect-conservation equations include production by irradiation and thermal sources; and
destruction by mutual recombination, migration to sinks as well as clustering into loops.
Interstitial clustering is assumed to occur by diffusion of interstitial atoms. Vacancy
loops, on the other hand, are assumed to form by an athenaal cascade-collapse process.
The density of such loops is determined as a result of the production of cascades and the
finite loop lifetime. Cascade overlap and coalescence are also included in the model.
The calculations are extended to the analysis of the radiation-induced changes In tensile
properties due to formation of interstitial and vacancy loops. A simple hardening model
reiaces the microstructural calculations to predictions of changes in tensile strength.
The results of this study show good agreement with hardening data for copper irradiated
in RTNS-II at room temperature. The results also provide insight on differences in nicro-
scructural results observed in various experimental studies on copper.
