Influence of crystal orientation on recovery and recrystallization in pure Tantalum
Résumé
Static recovery and recrystallization are known to be highly influenced by the microstructure of the plastically deformed state. Therefore, the inherited heterogeneity due to crystal plasticity highly defines the microstructure behavior during recovery and recrystallization not only in terms of kinetics but also in terms of physical mechanisms.
High purity tantalum (>99.99% wt.) is an excellent case study for several reasons, mainly because as a body centered cubic material, cross slip is expected to be highly activated. Therefore, the development of dislocation sub-structures during plastic deformation, highly dependent on the crystal orientation of the grains, induces the activated mechanisms for nucleation and recrystallization. For example, strain induced boundary migration nucleation was reported to be the main nucleation mechanisms in grains without sub-structures. In addition, the presence of dislocation sub-structures may lead in some specific cases of a non-familiar accelerative effect of recovery on recrystallization.
This presentation will cover new findings obtained on pure tantalum during the last ten years. Those findings are not specific to tantalum, they may concern all metallic alloys forming dislocation sub-structures.