Study of fundamental features of bias effect in metals under irradiation

Studies on bias mechanisms, such as the dislocation bias and production bias have so far been made in the Fe and Ni model crystals. In the present work the interaction between an edge dislocation and interstitial clusters has been mainly studied by computer simulation from the viewpoint of the production bias for Fe and Ni. Capture zones for interstitial clusters In (bundles of n crowdions, n=1, 2, 3, 5) to an edge dislocation line have been obtained, with the definition of the capture zone as the region where the binding energy is larger than kT=0.067 eV (T=500 °C). This shows increasing capture areas on the expansion side of the edge dislocation line with increasing size of interstitial clusters both in Fe and Ni. The energy change from the as-trapped state of the interstitial cluster to the absorbed state into the edge dislocation core was also calculated. This showed that the final stable configuration is a jogged state in Fe. This is also correct in Ni but only when the size of the interstitial cluster is larger than a certain value. These results give a confirmed basis to the production bias mechanism.