Diffusion and Thermal Conversion of Crowdions

Thompson and Buck have demonstrated by internal friction measurements that self‐interstitials in copper may exist in two configurations, a stable and a metastable one. The metastable configuration may be converted by thermal fluctuations into the stable configuration. The present paper develops a simple model for dislocation pinning by crowdions, taking into account thermal conversion. The results clearly indicate that the metastable interstitial in Cu migrates in one dimension, i.e., that it is a crowdion. The temperature dependence of the pinning rate is accounted for by a conversion energy barrier that is in agreement with other data.