パラジウム中の水素拡散に及ぼす転位の影響

抄録

Understanding the diffusion properties of hydrogen in metals, especially interactions between hydrogen and lattice defects such as dislocations, is essential in order to improve the performance and reliability of equipment associated with hydrogen. We investigate the effect of edge dislocations on hydrogen diffusion in face-centered-cubic (fcc) metals using molecular dynamics simulations of palladium-hydrogen as a model system. We find that the hydrogen diffusion in a perfect crystal without the dislocations is isotropic, whereas that in a system with the dislocations has anisotropy. In addition, our results predict high hydrogen diffusivity along the dislocation lines in high hydrostatic stress region with high hydrogen density after hydrogen accumulation caused by the interactions between hydrogen atoms and the dislocations. The activation energy of the hydrogen diffusivity in the system with the dislocations is estimated to be 0.10 eV, which is 38 % smaller than that in the perfect crystal.