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

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2001-12, Vol.319, p.484-489
• Main Authors: Khantha, M., Vitek, V., Pope, D.P.
• Format: Article
• Language: English
• Subjects: Brittle–ductile transition; Condensed matter: structure, mechanical and thermal properties; Cooperative dislocation generation; Exact sciences and technology; Fatigue, brittleness, fracture, and cracks; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Physics; Strain-rate effects
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/S0921-5093(01)01021-8

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.