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. Digital image correlation (DIC) will be used to quantify localised slip features which will be related to the underlying crystallography revealled by EBSD which also map intra-granular distributions of local stress and dislocation density.
This project will continue successful work that has focussed on Ti alloys, Ni alloys and stainless steel and would suit a graduate with a background in materials science, metallurgy or mechanical engineering.