Damage tolerance of nuclear graphite at elevated temperatures

Dong Liu*, Berdt Gludovatz, Harold S. Barnard, Martin Kuball, Ritchie Robert O.

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

28 Citations (Scopus)
336 Downloads (Pure)

Abstract

Nuclear-grade graphite is a critically important high-temperature structural material for current and potentially next generation of fission reactors worldwide. It is imperative to understand its damage-tolerant behaviour and to discern the mechanisms of damage evolution under in-service conditions. Here we perform in situ mechanical testing with synchrotron X-ray computed micro-tomography at temperatures between ambient and 1,000 °C on a nuclear-grade Gilsocarbon graphite. We find that both the strength and fracture toughness of this graphite are improved at elevated temperature. Whereas this behaviour is consistent with observations of the closure of microcracks formed parallel to the covalent-sp 2 -bonded graphene layers at higher temperatures, which accommodate the more than tenfold larger thermal expansion perpendicular to these layers, we attribute the elevation in strength and toughness primarily to changes in the residual stress state at 800-1,000 °C, specifically to the reduction in significant levels of residual tensile stresses in the graphite that are € frozen-in' following processing.

Original languageEnglish
Article number15942
Number of pages9
JournalNature Communications
Volume8
DOIs
Publication statusPublished - 30 Jun 2017

Structured keywords

  • CDTR

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