弦モデルによる転位ループの熱活性化過程の解析

概要

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We report an analytical study of thermally activated transport of perfect dislocation loops with highmobility in terms of a line tension model, where the dislocation loops are assumed to be flexible strings with line tension. The activation energy and saddle-point configuration of the dislocation loops are analytically expressed within the framework of the present model. The activation energy increases with the loop length and converges to a finite value. However, the features of the thermally activated motion remarkably changes depending on the loop length. If the dislocation loops are longer than a critical length L_c, the saddle-point configuration is the well-known double-kink type. On the other hand, if the dislocation loops are shorter than L_c, the saddle-point configuration is the so-called trivial solution, that is, the dislocation loops overcome the potential barrier without changing their shapes except for thermal fluctuations. The former is regarded as dislocation-like transport, while the latter is point-defect-like migration. Therefore, as the dislocation loops grow, a transition from point defect to dislocation substantially occurs.
Research Institute for Applied Mechanics, Kyushu Universityの論文
2005-09-00