Stainless steels and Ni base alloys are extensively used as structural materials due to their high corrosion resistance properties. However, it is also well known that these materials can be susceptible to environmentally assisted fracture, such as stress corrosion cracking (SCC), corrosion fatigue and hydrogen embrittlement when these materials are exposed to a reactive environment under loading. This project aims to advance understanding of how the microstructure and material composition of structural materials influences the fatigue crack growth rate enhancement and retardation using state-of-the-art materials characterisation.
Amongst the enabling factors, a susceptible microstructure is responsible for this kind of degradation phenomena, which depends on the manufacturing route, such as forging and welding. However, there is currently insufficient knowledge on the impact of the metallurgical quality of the material produced by such processes on the materials performance. It is critical, therefore, to have a fundamental understanding of the relationship between manufacturing and microstructure, so that potential degradation caused by changes to current manufacturing practices can be judged. This, in turn, requires a scientifically based understanding of the various underlying mechanisms that influence/control environmental degradation to enable a more accurate fatigue life prediction.
High-resolution secondary ion mass spectrometry (NanoSIMS) and stable isotopic labelling is emerging as an effective way to investigate and understand how chemistry affects degradation at the scale of the microstructure. Isotopically labelled (deuterated) water will be used to investigate hydrogen uptake during exposure to high temperature water to understand the role of hydrogen on dislocation dynamics, interaction with precipitates and subsequent embrittlement. This information can be used to tailor the microstructure (via heat treatments) to improve material performance. Isotopic labelling will also be used to understand oxidation and the effect of carbon diffusion enhanced by dislocation drag. The effect of detrimental elements, such as sulfur will also be explored.
The project will use the University of Manchester and Henry Royce Institute’s extensive high temperature testing capability to simulate extreme environments. Samples tested in demanding environment (including hydrogenated water, hydrogenated steam or high temperature CO2 environment) samples will then be subsequently analysed with the advanced analytical (electron and SIMS) microscopes at the university in order to obtain a mechanistic understanding of the controlling mechanisms of environmentally assisted degradation. The project will also benefit from the professional guidance and the significant expertise of leading industrial consultants.
Academic background of candidates
Applicants should have or expect to achieve at least a 2.1 honours degree in Materials Science, Mechanical Engineering with materials specialisation, Chemical Engineering, Physics, Chemistry or related disciplines.
At the University of Manchester, we pride ourselves on our commitment to fairness, inclusion and respect in everything we do. We welcome applications from people of all backgrounds and identities, and encourage you to bring your whole self to work and study. We will ensure that your application is given full consideration without regard to your race, religion, gender, gender identity or expression, sexual orientation, nationality, disability, age, marital or pregnancy status, or socioeconomic background. All PhD places will be awarded on the basis of merit.
If you have any questions about the application process, please contact the PGR Admissions Team ([Email Address Removed]).