Crack-tip plasticity and intrinsic toughening in nano-sized brittle amorphous carbon

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Most monolithic brittle materials are vulnerable to the failure by cracks because of a lack of intrinsic toughening mechanisms, such as the plasticity in the vicinity of the crack front. As a result, most of the efforts to mitigate the sudden failure of brittle ceramics have been focused on developing the extrinsic toughening mechanisms that hinder crack propagation behind the tip, such as the fiber bridging. In this work, we experimentally demonstrate that the intrinsic toughening arises even in the brittle monolithic ceramic material such as diamond-like carbon (DLC) when its external dimension reduces down to sub-micron scales. This unique phenomenon owes its origin to the decrease of the crack driving force in the small samples, which in turn enables them to bear high enough stresses to activate the local atomic plasticity. Through nanomechanical tensile and bending experiments, electron energy loss spectroscopy analysis, and finite element method for stress distribution calculation, we confirmed that the local atomic plasticity associated with sp(3) to sp(2) rehybridization is responsible for the intrinsic toughening.
Publisher
PERGAMON-ELSEVIER SCIENCE LTD
Issue Date
2020-04
Language
English
Article Type
Article
Citation

INTERNATIONAL JOURNAL OF PLASTICITY, v.127

ISSN
0749-6419
DOI
10.1016/j.ijplas.2019.102642
URI
http://hdl.handle.net/10203/273806
Appears in Collection
NE-Journal Papers(저널논문)
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