J. Phys. IV France 09 (1999) Pr9-127-Pr9-136
Superposition of external and internal stress components in γ/γ'-microstructures and their effect on γ-channel dislocationsM. Probst-Hein1, A. Dlouhy2 and G. Eggeler1
1 Institut für Werkstoffe, Ruhr-Universität Bochum, 44780 Bochum, Germany
2 Institute of Physics of Materials, Zizkova 22, 61662 Brno, Czech Republic
Glide and climb forces on γ-channel dislocations in γ/γ'-microstructures are calculated considering a simplified scenario involving discrete dislocations. The influence of (i) misfit stresses, (ii) volume fraction of γ'-particles, (iii) the density of channel dislocations and (iv) the external stress is considered. In the approach taken in this study we superimpose misfit stresses from thermo-elastic FEM-calculations with applied stresses and with stresses caused by discrete channel dislocations. The calculations are based on previous mechanical and microstructural results where a number of dislocation reactions were observed using TEM and identified as relevant microstructural elements of the overall mechanism of high temperature and low stress creep. Preliminary results show that in a realistic microstructural scenario there is a limit to the number of dislocations which can enter a γ-channel by glide (in the absence of recovery processes). This number depends on γ'-volume fraction and on γ/γ'-misfit. Moreover it was found that glide and climb forces depend on the position of the dislocation segment in the channel and that there is a general tendency to push dislocations out of the channels.
© EDP Sciences 1999