Real-Time Observation of Nanoscale Kink Band Mediated Plasticity in Ion-Irradiated Graphite: An In Situ TEM Study
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Summary
This summary is machine-generated.Ion irradiation transforms brittle graphite into a ductile material by forming kink bands. These kink bands accommodate strain, preventing failure and enhancing toughness in nuclear reactor components.
Area Of Science
- Materials Science
- Nuclear Engineering
- Solid Mechanics
Background
- Graphite IG-110, a synthetic polycrystalline material, is utilized as a neutron moderator in nuclear reactors.
- Graphite exhibits inherent brittleness, which is exacerbated by radiation damage at room temperature.
Purpose Of The Study
- To investigate the effects of ion irradiation on pre-existing defects in graphite.
- To understand how these defects influence the material's response to external loads.
Main Methods
- Micropillar compression tests were conducted.
- In situ nanoindentation within Transmission Electron Microscopy (TEM) was employed for both pristine and irradiated samples.
Main Results
- Pristine graphite samples failed catastrophically under load.
- Ion-irradiated graphite (2.8 MeV Au<sup>2+</sup>, 4.378 × 10<sup>14</sup> cm<sup>-2</sup>) exhibited extensive plasticity and no failure at room temperature.
- In situ TEM revealed nanoscale kink band structures that accommodated large strains by closing defects and cracks.
Conclusions
- Compressive stress from ion irradiation induces kink bands by transforming buckled basal layers.
- Applied mechanical load promotes kink band nucleation and motion, enabling significant plastic strain accommodation.
- Graphite's microstructural non-uniformity localizes strain, making kink bands the primary mechanism for enhanced toughness in this brittle material.
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