Exploring dislocation mobility in the presence of abundant point defects – Materials Strand Project

Supervisor: Christopher Race (University of Sheffield)

The materials of a fusion reactor must survive for many years in an incredibly harsh environment. This includes constant bombardment by high energy neutrons, which smash into the materials, rearranging the atoms in our carefully engineered metallic alloys. We need to understand how this process of irradiation damage will change the properties of the alloys and perhaps limit their useful lives.

In this harsh environment, the forces experienced by materials can cause them to slowly deform in a process known as creep. Because of the long timescales involved, experimental measurement of creep can be very challenging and so simulations are often used to aid our understanding and make predictions about materials lifespan.

One approach to these simulations is the crystal plasticity finite-element method (CPFEM). These models encode analytical representations of a wide variety of features of real and complex systems, treating, for example, various mechanisms of hardening. To make accurate predictions, the equations used must be motivated by physically sound models.

Many of these models are focused on predicting plastic behaviour in the absence of irradiation, where empirical data for calibration and validation are readily available. In the fusion scenario, irradiation gives rise to an abundance of point defects, which change the mechanisms by which plastic deformation occurs, and empirical data are limited.

In this project, you will use classical molecular dynamics simulations to study the mechanisms by which dislocation defects (responsible for plastic deformation) move around when large numbers of point defects are present. You will characterise this motion and build analytical expressions to incorporate the mechanisms in crystal plasticity models.

This project is focused on materials simulation and analytical modelling. It will suit a student interested in computational and theoretical work. Training will be provided in all the core techniques and in the materials background to the project. You’ll need to do some coding, but only in an easy-to-use scripting language like Python, which you can learn as part of the project. There won’t be any hard-core software development. The project would particularly suit you if you enjoyed the mathematical elements of your undergraduate course, whether that was in physics, materials, engineering or a related discipline.

The project will be mainly based in Sheffield. There will be opportunities for travel to CCFE in Culham and for international travel for conferences and collaboration. The extent of travel will be tailored to the needs and desires of the student to make sure the project is as accessible to all, regardless of personal circumstances.

This project is offered by University of Sheffield. For further information please contact: Christopher Race (christopher.race@sheffield.ac.uk).

This project may be compatible with part time study, please contact the project supervisors if you are interested in exploring this.