Extension of the Unsaturable Trap Model to One‐Dimensional Interstitial Migration

For most f.c.c. metals the increase of the electrical resistivity due to stage‐II temperature irradiation may be interpreted in terms of trapping of mobile interstitials at unsaturable traps. This model originally elaborated for interstitials migrating in three dimensions predicts that the inverse of the production rate of defects retained in an irradiation‐exposed sample increases linearly with the defect concentration. Using three different methods (rate equation approach, diffusion theory, and a computer simulation technique) it will be shown that this relationship remains valid if the mobile interstitials are off‐line crowdions and thus constrained to a long‐range migration in one dimension. It is therefore not admissible to draw any conclusions about the nature of self‐interstitials in f.c.c. metals from radiation damage curves measured at stage‐II temperatures, contrary to what has repeatedly been done in the literature.