[SY-E8] Symposium E-8

[SY-E8] Effect of hydrogen on the vacancy diffusion in metals

^○Jun-Ping Du^1,2, W.T. Geng³, Kazuto Arakawa⁴, Shigenobu Ogata^2,1 (1.Elements Strategy Initiative for Structural Materials, Kyoto University, Japan, 2.Department of Mechanical Science and Bioengineering, Osaka University, Japan, 3.University of Science and Technology Beijing, China, 4.Department of Materials Science, Faculty of Science and Engineering, Shimane University, Japan)

Hydrogen can be either an intentional constituent or unwelcome impurity in metals. The fact that excess hydrogen can enhance greatly the self-diffusion of atoms in metals has been explained by the appearance of superabundant vacancies, because the vacancy formation energy decreases substantially with increasing H concentration, while individual vacancy diffusion is supposed to be slowed down due to the increased jumping energy barrier of H-vacancy complexes based on the previous first-principles studies. Here, performing first-principles calculations of appearance probability of possible H-vacancy configurations and activation energy of possible vacancy jumping pathways in combination with molecular dynamics (MD) simulations, we found at certain H concentrations and temperatures, the diffusivity of vacancy in face-centered cubic Cu can be accelerated by H, which is caused by H-enhanced diffusion attempt frequency and environmental H-assisted vacancy diffusion pathway. The MD simulations demonstrated that the promoting effect of H can also be found in dynamical processes. The uncovered H-vacancy diffusion processes in metals can advance our understanding of the H behavior in metals.