Atomistic simulations of nanocrystalline U 0.5 Th 0.5 O 2 solid solution under uniaxial tension

Abstract

Abstract Molecular dynamics simulations were performed to investigate the uniaxial tensile properties of nanocrystalline U 0.5 Th 0.5 O 2 solid solution with the Born–Mayer–Huggins potential. The results indicated that the elastic modulus increased linearly with the density relative to a single crystal, but decreased with increasing temperature. The simulated nanocrystalline U 0.5 Th 0.5 O 2 exhibited a breakdown in the Hall–Petch relation with mean grain size varying from 3.0 nm to 18.0 nm. Moreover, the elastic modulus of U 1- y Th y O 2 solid solutions with different content of thorium at 300 K was also studied and the results accorded well with the experimental data available in the literature. In addition, the fracture mode of nanocrystalline U 0.5 Th 0.5 O 2 was inclined to be ductile because the fracture behavior was preceded by some moderate amount of plastic deformation, which is different from what has been seen earlier in simulations of pure UO 2 .