Exploring dislocation mobility in the presence of abundant point defects

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.