High temperature mechanical testing of quasi-brittle materials

Quasi-brittle materials are proposed for load-bearing roles in nuclear fission (graphite, such as in TRISO compacts) and nuclear fusion (SiC-SiC). The behaviours of these materials when either unirradiated and tested at high temperature, or irradiated and tested at room temperature, are reasonably well understood (https://doi.org/10.1016/j.carbon.2020.03.020, https://doi.org/10.1016/j.carbon.2020.09.072), but there is limited mechanical data for either irradiated SiC-SiC and graphite at high temperature (particularly for graphite grades relevant to the next generation fission reactors), and virtually no high temperature fracture toughness data in the irradiated condition. These tests are challenging to perform due to the need for operation in shielded environments such as hot cells. Reliable test data are needed for structural integrity assessments, and also to qualify new materials.

This project aims to develop a methodology for high temperature mechanical testing of irradiated quasi-brittle materials. Digital Image Correlation (DIC) will used to measure the surface displacement field from deformation of small specimens, with inverse analysis applied to extract the properties of high temperature modulus, strength, and fracture toughness from a single test.  In-situ imaging and diffraction analysis at high temperatures are planned at the UK Diamond Light Source (i12, engineering beamline) to investigate the damage mechanisms. The project will study non-radioactive materials, but the techniques developed will be directly transferrable to testing of irradiated materials. The project is suitable for graduates with an engineering, mathematical or physical sciences background.