Fracture behavior of grain boundaries in (U,Pu)O ₂ fuels: An atomistic study

Abstract Classical atomistic simulations using the Cooper–Rushston–Grimes potential were carried out to observe the stability and the fracture properties of six special grain boundaries in (, . The formation energy decreases as a function of Pu content, while the cleavage energy increases. Mechanical tensile tests were performed on these grain boundaries to calculate the fracture stress and fracture energy. Some grain boundaries exhibit a phase transition prior to brittle fracture. The conditions for the appearance of this phase transition depend on the stress field values before the fracture, which are influenced by the Pu content. The Pu content appears to enhance the fracture resistance of the grain boundaries, as indicated by the fracture energy and cleavage energy.