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A macro-scale ruck and tuck mechanism for deformation in ion-irradiated polycrystalline graphite.
- Source :
-
Carbon . Mar2021, Vol. 173, p215-231. 17p. - Publication Year :
- 2021
-
Abstract
- A vein structure, which becomes more pronounced with increasing ion dose, was found on the surface of polycrystalline HOPG (highly oriented pyrolytic graphite) implanted by ex situ C+ (up to 1.8 × 1017 ions/cm2), and in situ Ar+ in a transmission electron microscope (TEM). These veins are found to be independent of the crystallographic orientations and are associated with the formation of pores. Underneath the veins, a triangular-shaped core was formed with the graphite platelet inside the core displaced up towards the surface. A macro-scale 'ruck&tuck' geometry was thus generated at these triangle structure boundaries. Progressive movement of dislocations along basal planes during irradiation was observed, and a mechanistic model was proposed on this basis to explain the vein formation. A small increase of c -spacing was observed with irradiation but it is believed that macro-scale vein formation plays a more vital role in the dimensional and property changes in polycrystalline graphite, especially when a stress gradient is present. The model proposed also explains the change of thermal expansion in HOPG with irradiation. Together with Heggie's 'ruck&tuck' and Barsoum's 'ripplocations' models, the present model is considered to have provided an additional experimentally proven mechanism responsible for irradiation behaviour in graphite materials. Image 1 [ABSTRACT FROM AUTHOR]
- Subjects :
- *GRAPHITE
*PYROLYTIC graphite
*TRANSMISSION electron microscopes
*THERMAL expansion
Subjects
Details
- Language :
- English
- ISSN :
- 00086223
- Volume :
- 173
- Database :
- Academic Search Index
- Journal :
- Carbon
- Publication Type :
- Academic Journal
- Accession number :
- 148187754
- Full Text :
- https://doi.org/10.1016/j.carbon.2020.10.086