Strain-rate dependent mechanism of cooperative dislocation generation: application to the brittle-ductile transition

[摘要] A strain-rate dependent mechanism of cooperative dislocation generation in loaded solids above a critical temperature is described. The massive dislocation activity, which commences near the crack tip at the brittle-to-ductile transition temperature is modeled in terms of this mechanism. The strain-rate dependence of the critical temperature arises from the glide of both pre-existing dislocations and dislocations which are 'thermally nucleated' below the critical temperature by the cooperative process, Depending on their relative contributions. the apparent activation energy associated with the brittle-to-ductile transition temperature is either equal to or larger than the activation energy for dislocation motion. We compare the predictions of the model with observations in TiAl. (C) 2001 Elsevier Science B.V. All rights reserved.

[发布日期] 2001-12-01

[效力级别]  Proceedings Paper

[关键词] cooperative dislocation generation;brittle-ductile transition;strain-rate effects