This project is concerned with the role of microstructure in the fatigue resistance of novel high strength Light weight nanostructured alloys. A new family of rapid solidified alloys show good mechanical properties with combined high strength and low density, these alloys have the potential to be used in pistons in car engines and replace Ti-alloys in gas turbines; the consequent reduction in weight and inertial forces will reduce fuel consumption and increase power output.
Tests performed to data show these alloys have very good fatigue resistance, but there have been no fundamental studies to investigate the mechanisms for this; the hypothesis is that initiated fatigue cracks are arrested at interfaces between the matrix and reinforced zones. If so, then the strain paths arising from process variations during forging may have a significant effect on microstructure and the local fatigue properties. To study this, a range of microstructures of a nanostructured Al alloy obtained by different heat treatments and processing conditions will be produced and tested to correlate fatigue crack initiation and growth with the microstructure; importantly the interactions between arrested fatigue cracks and local microstructure will be studied using advanced electron microscopy, including high resolution EBSD and TEM of FIB-milled selected regions, to develop mechanistic models for fatigue resistance. The interactions between microstructure and crack propagation may also be studied by in situ high-resolution computed tomography (Marrow, T.J. et al (2014) http://dx.doi.org/10.1016/j.ijfatigue.2014.04.003).
The project is suitable for students with an engineering, physics or materials background and will involve techniques such as electron microscopy, materials processing digital image correlation, finite element modelling and computed X-ray tomography.