The design of materials for extreme (high temperature, high flux) applications, like those experienced in fission and fusion reactors, requires an atomic-level understanding of the origins and evolution of the damage that is sustained in these environments. This necessitates a way to characterize these materials with the capacity to identify individual atoms and precisely locating them on their three dimensional crystal lattice. However, there are very few techniques from which such information can be routinely accessed. Field Ion Microscopy (FIM) is characterisation technique capable of imaging every atom on the surface of a very sharp needle-shaped specimen. If all atoms can be precisely imaged on the 3D lattice then so too can irradiation induced damage be observed even down to the level of a single vacancy.
The current state-of-the-art atom probe instruments installed at Oxford have digital FIM capability. The move away from the traditional phosphor screens to digital imaging in the FIM experiments has both significant challenges and exciting new potential. Although there have been some recent exciting work in the development of digital FIM, research in this area currently remains very limited.
This project seeks to further develop digital FIM, working towards making this a routinely deployable characterisation tool. In particular it will focus on the application of the technique to investigate microstructural degradation at the atomic scale in material components subject to the extreme conditions of the reactor environment. This includes directly imaging irradiation damage to the crystal lattice, such as voids and dislocations, and precipitate formation and evolution in materials such as tungsten and T91 steel. The focus will initially be on conventional 2D imaging but will ultimately aim for 3D analyses by extending the current tomographic algorithms pioneered in Oxford.