Irradiation-induced creep in nanocrystalline Cu alloys

Irradiation-induced creep in nanocrystalline Cu was simulated with the aim of analyzing the microscopic mechanism driving creep. The systems included various immiscible mixtures where the solute atom segregated at grain boundaries and led to grain size stabilization. The small grain size in the nanocrystals prevents the development of dislocation-based dynamics within the grains, and gives rise to alternative mechanisms that are based on grain-boundary plasticity. We show a correlation between observed creep rates and the climbing of dislocations at the grain boundaries. Due to the simple structure of Cu-based alloys, they can serve as model systems for investigating irradiation-induced creep. This establishes the basis for a mean-field model that can predict the creep compliance of a sample as a function of its structure and composition. The model reproduces recent experimental measurements. • We used molecular dynamics to show that dislocation climb drives irradiation-induced creep. • We applied a recently-introduced method to track dislocation motion in grain boundaries. • We developed a model predicting creep compliance based on solute segregation effects. • Our simulations reveal solute-specific impacts on creep and grain boundary flux. • We validated the model with experiments, linking atomic-scale and macroscopic behavior.