In-situ/operando mapping of hydrogen in metals with multi-modal X-ray imaging

Hydrogen embrittlement (HE) is an unsolved industrial challenge posing a significant constraint on the development of storage, distribution and end-use hydrogen technologies. The specific origin of HE has long been a topic of debate and no precise proposed mechanism exists that is consistent with all the observed HE consequences. In particular, progress in HE mechanisms understanding is hindered by the lack of experimental data regarding hydrogen trapping, the phenomena taking place during cracking and the interaction of hydrogen with microstructural features. Furthermore, to evaluate the behaviour of materials in real-world conditions, the validity of these mechanisms need to be assessed in-situ and dynamically over a broad range of environments - e.g. temperature (from cryogenic to combustion), high pressure, gaseous mixture and varying load. Are existing HE mechanisms still valid at liquid hydrogen temperatures? How is diffusion affected by dynamic conditions, for example when changing temperature and pressure? None of the currently available characterization methods can be used to run in-situ and operando experiments which allow simultaneous mapping of hydrogen within the microstructure whilst assessing the mechanical response under dynamic conditions of load and environment.

The project aims to develop new multi-modal X-ray imaging methods to measure the hydrogen content at the microstructural scale during in-situ/operando experiments. Crucially, artificial intelligence will be used to automate experiments, data collection and ‘live’ analysis of the generated data. The new instrument will be capable of simulating a wide range of real-world environments, mapping hydrogen distribution within microstructures, and exploring hydrogen-induced fracturing in operando. This work will contribute to deepen our understanding of the mechanisms occurring during hydrogen facilitated fracture and the role of hydrogen trapping. If the fracture progress can be understood, and we learn how to design more benign traps, it will be possible to develop metals with mechanical properties that increase in hydrogen, particularly ductility and fracture toughness. The student will work within a multi-disciplinary team of researchers from several institutions, including STFC, Oxford Engineering and Diamond light Source.