High-Temperature Discrete Dislocation Plasticity
Event details
| Date | 03.04.2012 |
| Hour | 13:15 › 14:15 |
| Speaker | Dr. Amine Benzerga, Texas A&M University, USA |
| Location | |
| Category | Conferences - Seminars |
At low homologous temperatures, the plastic deformation of metals is controlled by the glide of dislocations and a host of athermal interactions with other dislocations, precipitates and grain boundaries. In discrete dislocation dynamics simulations of such deformation processes, temperature effects may enter through dislocation mobility and lattice friction as well as cross-slip. At temperatures greater than about 1/3 of the melting point, the climb of dislocations becomes increasingly important leading to phenomena such as creep and dynamic recovery. The modeling of climb as a nonconservative motion generally requires the concurrent modeling of dislocation motion and the diffusion of point defects into the cores of the dislocations. In this paper we report on a self-consistent formulation of high-temperature discrete dislocation plasticity in finite bodies, which couples dislocation dynamics with vacancy diffusion theory. To address the issue of disparate time scales related to glide and climb mechanisms, an adaptive multi-time stepping algorithm is used in the numerical implementation of the theory. We then present a series of deformation analyses at constant applied stress in single crystals. We show that two regimes of power-law creep naturally emerge in the simulations, as affected by the applied stress and test temperature. We also systematically quantify the power law exponent in either regime and the part of the strain rate that results from mass transport through the diffusive flow of vacancies due to pressure gradients
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