Simulation of Intergranular Void Growth Under the Combined Effects of Surface Diffusion, Grain Boundary Diffusion, and Bulk Creep

Creep rupture is currently a major concern for next-generation nuclear reactor components, and many commonly used lifetime estimates are based on how quickly intergranular voids grow. Void growth is caused by three processes: diffusion along the void surface, diffusion along the grain boundary, and creep of the surrounding grains. Previous modeling efforts have only considered two of these three processes at a time. Here we present finite element simulations of void growth under the influence of all three mechanisms simultaneously. To our knowledge, these are the first such simulations to be reported in the literature. Based on our simulations, we develop quantitative criteria for quasi-equilibrium and crack-like void growth and compare them to previous results. Furthermore, we find that void growth is highly accelerated during the primary creep regime. Our results promise to aid in the development of microstructure-sensitive material strength models for next-generation nuclear reactor components.