Overcoming old barriers in the thermally-activated glide of dislocations
Event details
| Date | 24.09.2013 |
| Hour | 13:15 › 14:15 |
| Speaker |
David Rodney, Institut Lumière Matière, University of Lyon, France Bio : David Rodney is a Professor of Physics at the University of Lyon. After a PhD in 1999 working between CEA Saclay and Brown University and a post-doc at ONERA Châtillon in 2000-2001, he became an associate Professor at Grenoble Institute of Technology in 2001 and moved to Lyon in 2013. He was also a visiting scientist at M.I.T. in 2008-2009. He has co-authored more than 60 papers in the field of the multiscale modeling of deformation in materials including crystalline metals, amorphous glasses and fibrous materials. Since 2012, he serves as associate Editor for Acta Materialia. |
| Location | |
| Category | Conferences - Seminars |
Abstract : Although thermally-‐activated plasticity has been studied for over 50 years, vast aspects of this process remain unclear, in particular regarding modeling. Reasons range from limitations in continuum modeling to include atomistic effects, difficulties in developing realistic potentials, interplay between complex processes, such as collective effects, dynamical effects, cross-‐slip, … In this seminar, we will present recent progresses made in the modeling of probably the best-‐known dislocation subjected to thermally-‐activated glide, the screw dislocation in body-‐centered cubic crystals. We will show that a static approach, combining saddle-‐point search methods (the Activation-‐Relaxation Technique and Nudged Elastic Band method) to identify energy pathways and the Transition State Theory (TST) to predict kinetics, allows understanding and modeling accurately the dislocation thermally-‐activated glide. Our approach makes use of a line tension model parameterized on atomistic simulations, which can predict dislocation kinetics at high temperatures in the classical regime. At low temperatures, we will show that the well-‐known fact that atomistic calculations overestimate the Peierls stress compared to experiments is due to the zero-‐point energy motion of atoms, which helps dislocation glide at low temperatures compared to classical calculations and had not been previously accounted for in atomistic simulations, as reported recently in Proville, Rodney, Marinica, Nature Materials, doi: 10.1038/nmat3401 (2012).
Practical information
- General public
- Free
Organizer
- IGM
Contact
- Géraldine Palaj