Defect cluster formation in displacement cascades in copper

Extensive study of primary damage in displacement cascades in metals by com puter simulation has shown that the total number of defects produced is sig nificantly lower than predicted by the Norgett, Robinson and Torrens (NRT) model and that a significant fraction of the self-interstitials forms gliss ile clusters. However, there is a lack of variety of defect types observed in cascade simulation, which, in many cases, makes it difficult to explain experimental data. For example, experiments on copper show efficient produc tion of stacking fault tetrahedra (SFTs) but they were not observed systema tically in computer simulation. To consider this further, extensive simulat ion of displacement cascades in copper has been performed using two differe nt interatomic potentials, a short-range many-body potential(MBP) and a lon g-range pair potential (PP). Primary knock-on-atom (PKA) energy in the rang e 2-20 keV and temperatures of 100 and 600 K were considered. Special atten tion was paid to cascade statistics and the accuracy of simulation in the c ollision stage. The former required many simulations for each energy wherea s the latter involved a modification of the simulation method to treat a ho t region with high accuracy by applying a smaller time step. Results showin g the variety of clusters observed, e.g. SFTs, glissile and sessile interst itial clusters, and faulted and perfect interstitial dislocation loops, are presented. (C) 2001 Elsevier Science B.V. All rights reserved.