Characterization of dislocation interactions in olivine using electron tomography

Abstract

We have investigated by electron tomography, in a transmission electronic microscope, the interactions between dislocations in olivine single crystals and polycrystals deformed in axial compression at T < 1000 °C (T < 0.5T_m). Dislocations are mostly of the [0 0 1] type, except in the polycrystal where [1 0 0] and [0 0 1] dislocations have been activated. A few 〈1 0 1〉 junctions have been found and characterized. Many collinear interactions have been identified either involving direct interactions between crossing dislocations of opposite Burgers vectors or indirect interactions between dislocations gliding in parallel planes and sessile dislocation loops. We suggest that collinear interaction, already identified as the primary source of strain hardening in FCC metals, is the main dislocation interaction mechanism in olivine deformed at temperatures below 1000 °C.

Keywords:

• dislocation
• junction
• collinear interaction
• TEM
• electron tomography
• olivine

Acknowledgements

The TEM national facility in Lille is supported by the CNRS (INSU) and the Conseil Régional du Nord Pas de Calais, France.

Additional information

Funding

This work was supported by the Marie Curie fellowship awarded to Sylvie Demouchy (PoEM: Plasticity of Earth Mantle, FP7-PEOPLE-20074-3-IRG) [grant number 230748-PoEM]; the European Research Council within the Seventh Framework Program (FP7) [grant number 290424 – RheoMan to Patrick Cordier].