|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||Thermo-mechanical Response of Materials with Special Emphasis on In-situ Techniques
||Real Time 3-D X-ray Computed Micro-tomography Study of the Strength and Toughness of Nuclear Graphite between 25° and 1000°C
||Dong Liu, Bernd Gludovatz, Harold S. Barnard, Martin Kuball, Robert O. Ritchie
|On-Site Speaker (Planned)
Nuclear-grade graphite is a vital high-temperature material in nuclear reactors. As its properties are complex and quasi-brittle due to a porous, high-defect, multi-phase structure, it is imperative to understand its mechanisms of damage evolution under high-temperature in-service conditions. To achieve this under load and at temperature, we have performed mechanical testing coupled with in-situ synchrotron x-ray computed micro-tomography to determine the strength and fracture-toughness behavior of Gilsocarbon graphite at 25°-1000°C, with simultaneous real-time 3-D imaging. Contrary to behavior in most materials, the graphite’s strength and toughness are improved at elevated temperatures. Whereas this behavior is consistent with observations of the closure of microcracks formed parallel to the covalent-sp2-bonded graphene layers at 1000°C, which accommodate the 10-fold larger thermal expansion perpendicular to these layers, we attribute the elevated strength and toughness to changes in the residual stress-state at 800°-1000°C, specifically to a reduction in significant residual tensile stresses “frozen-in” following processing.
||Planned: Supplemental Proceedings volume