The stress-driven migration of point defects to a slowly moving crack

Author: Streitenberger, Peter

Source: Philosophical Magazine, Volume 84, Number 23, August 11, 2004 , pp. 2455-2470(16)

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Abstract:

The migration kinetics of point defects near a slowly moving brittle crack are studied under the condition of pure drift. In the pure-drift approximation it is assumed that the point-defect flow in the vicinity of a crack tip is dominated by the elastic interaction between the stress field of the crack and a point defect and that concentration gradient effects can be neglected. While such a pure-drift approach has been shown to be useful to calculate the short-time diffusion kinetics of impurity-induced subcritical crack growth, previous applications are based on the drift solutions for a stationary crack. In the present paper, the first-order drift diffusion equation for a slowly moving crack at uniform velocity is solved. This yields the flow lines of the point defects and the impurity segregation rate directly in terms of the crack growth rate. The flow line patterns reveal important insights with respect to the point-defect migration kinetics near a steadily advancing crack. Although the calculation is entirely elastic, it is shown that the present drift model maintains some relevance also in the presence of a plastic zone ahead of the crack tip.

Document Type: Research article

DOI: http://dx.doi.org/10.1080/14786430410001692833

Affiliations: 1: Otto-von-Guericke-UniversitÄt Magdeburg Institut fÜr Experimentelle Physik Abteilung Materialphysik Postfach 4120 D-39016 Magdeburg Germany

Publication date: 2004-08-01

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