Invited Lecture
Dislocation climb and annealing in 3D dislocation dynamics simulations

Reliable thermal and irradiation creep lifetime prediction is a critical aspect in the design of high-temperature materials used in the aerospace and nuclear components. Critical examples include the mechanical behavior of zircaloy fuel cladding in fission-type water-cooled reactors and the deformation of tungsten in Plasma-Facing Components (PFC) in fusion reactors. These components may experience severe deformation and failure by creep, mediated primarily by dislocation climb and climb-assisted glide. One difficulty with current phenomenological models used in design is that they fall short of predicting creep behavior of irradiated materials outside the data range of the underlying experimental database. This difficulty is exacerbated by the fact that experimental creep tests often provide a limited description of the true long-term response of materials. In order to overcome these limitations, we develop here a predictive model of dislocation climb and annealing at high-temperature and under irradiation. The developed model is based on three-dimensional (3d) Dislocation Dynamics (DD) simulations of climb and glide processes, coupled to a continuum vacancy diffusion boundary value problem (BVP). The unique features of the model are: (1) the solution is available in finite domains to study the effects of grain size on annealing and recovery, and (2) 3d dislocations can undergo simultaneous glide and climb at vastly different time scales. Applications of the model will be shown for BCC tungsten, which is widely considered for PFC applications.