In the (very) high cycle fatigue regime crack initiation and short fatigue crack growth dominate fatigue lives. We have developed novel ultrasonic methods for very rapid (~106 cycles in <1 min) fatigue testing of very small (~0.5 to 200 µm across) material volumes cut by either FIB or laser micro-machining. Focussing the testing down to a small region allows the progression of deformation to be followed in detail for which a range of characterisation methods will be used. Secondary electron imaging in SEM will allow a rapid assessment of slip feature development and crack formation, while electron channelling contrast imaging will allow assessment of local dislocation structures. AFM will be used to quantify slip step heights and surface roughening which will be related to the underlying crystallography revealled by EBSD which also map intra-granular distributions of local stress and dislocation density.
The project is in collaboration with Rolls Royce who will provide a top-up to student stipend and some funds for research. There is also the possibility of spending some time on placement at Rolls Royce. The project aims at developing underpinning mechanistic understanding of the effects of surface condition, temperature and environment on fatigue in superalloys.
This project would suit a graduate with a background in materials science, metallurgy or mechanical engineering with a strong interest in advanced aerospace materials.
The description above outlines a possible new research project being offered to prospective new postgraduate students.