Sep 16 – 18, 2024
Granada
Europe/Madrid timezone

In-situ observation of deformation mechanisms in fine-grained nuclear graphite by high temperature disc compression

Sep 18, 2024, 9:00 AM
25m
Granada

Granada

Speaker

James Marrow (University of Oxford)

Description

Evaluating structural integrity requires knowledge of the distribution of, and relationship between, stress and strain as well as how the microstructure accommodates damage. New candidate graphites possess different microstructures to previous grades; there is a need to validate materials understanding on these new graphite grades, as well as collect data at relevant temperatures for materials qualification. In this work, small Brazilian disc specimens of fine grained graphite (diameter 5 mm) were loaded in diametral compression at elevated temperatures whilst observed in-situ using Synchrotron X-ray radiation on beamline i12 at the UK Diamond Light Source. Temperatures of 800 °C were achieved via resistance heating. Elastic strains and bulk strains were measured pseudo-simultaneously via transmission-diffraction mapping and digital image correlation of radiographs respectively. The spatial correlation of these strains has been used to investigate the deformation behaviour in compression and tension, including non-linear effects due to tensile damage mechanisms. A change in crystallographic texture with strain was also quantified via the Bacon Anisotropy Factor. The observed effects of temperature and strain provide new insights into the crystal deformation mechanisms of graphite microstructures. Demonstrating the viability of this experimental method for testing small scale samples also constitutes an important first step in building a testing regime suitable for investigating damage tolerance in irradiated material at elevated temperatures.

abstract Talk

Primary author

James Marrow (University of Oxford)

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