Modelling the thermal strength degradation of CuCrZr for use in plasma facing components

The adoption of nuclear fusion as a practical energy source is limited by the availability of materials that can withstand the extreme environment experienced by plasma-facing components. Materials development can be significantly accelerated by using computational materials modelling tools, capable of predicting the microstructure evolution during processing and service, and its effects on the properties of the materials. This is especially relevant in fusion applications in which operating conditions will be difficult and costly to replicate experimentally. This study presents a predictive model for the precipitation kinetics in CuCrZr alloys, a potential heat sink material for divertor target designs. A multi-class Kampmann-Wagner numerical modelling framework was used to predict the evolution of the precipitate size distribution during heat treatment and in service. The model was calibrated with experimental data obtained from short-term heat treatments ranging from 1-[Figure presented] within a temperature range of 400-[Figure presented] to establish temperature-dependent model parameters. The calibrated model was then used to predict long-term coarsening behaviour up to [Figure presented] over the same temperature range. Precipitate coarsening was associated with a maximum decrease in the material strength of 29% from the peak-aged material over the investigated temperature range, which is supported by measured hardness data. Furthermore, by simulating cycling heating due to reactor plasma instability, it was predicted that material strength can decrease by 44% from the peak-aged condition.