Dislocation screening and the brittle-to-ductile transition: A Kosterlitz-Thouless type instability.

We propose a new model for the brittle-to-ductile transition based on the Kosterlitz-Thouless concept of dislocation screening. In this model, thermal fluctuations assisted by the applied stress drive the spontaneous generation of dislocations and the instability occurs well below the melting temperature. In the limit of zero stress, our model reduces to the Kosterlitz-Thouless theory of the melting transition, and, in the opposite limit of zero temperature, we obtain the Rice-Thomson result for the brittle-to-ductile transition. Disciplines Engineering | Materials Science and Engineering | Semiconductor and Optical Materials This journal article is available at ScholarlyCommons: http://repository.upenn.edu/mse_papers/230 VOLUME 73, NUMBER 5 P H YSICA L R EV I EW LETTERS l AUCUST f 994 Dislocation Screening and the Brittle-to-Ductile Transition: A Kosterlitz-Thouless Type Instability M. Khantha, D. P. Pope, and V. Vitek Department of Materials Science and Engineering, University of PennsylvaniaP, hiladelphia, Pennsylvania l9104 (Received 22 February 1994) We propose a new model for the brittle-to-ductile transition based on the Kosterlitz-Thouless concept of dislocation screening. In this model, thermal Auctuations assisted by the applied stress drive the spontaneous generation of dislocations and the instability occurs well below the melting temperature. In the limit of zero stress, our model reduces to the Kosterlitz-Thouless theory of the melting transition, and, in the opposite limit of zero temperature, we obtain the Rice-Thomson result for the brittle-to-