Diffusion behavior of hydrogen isotopes in tungsten revisited by molecular dynamics simulations

• 来源期刊: 中国物理B（英文版）
• 关键词: hydrogen isotopes tungsten diffusion molecular dynamics
• 年，卷（期）: 2018,（7）
• 页码范围: 302-310
• 页数: 9页
• 语种: 英文
• DOI: 10.1088/1674-1056/27/7/073103

摘要

Molecular dynamics simulations were performed to study the diffusion behavior of hydrogen isotopes in single-crystal tungsten in the temperature range of 300–2000 K. The simulations show that the diffusion coefficient of H isotopes exhibits non-Arrhenius behavior, though this deviation from Arrhenius behavior is slight. Many-body and anharmonic effects of the potential surface may induce slight isotope-dependence by the activation energy;however, the dependence of the pre-factor of the diffusion coefficient on the isotope mass is diminished. The simulation results for H-atom migration near W surfaces suggest that no trap mutations occur for H atoms diffusing near either W{100} or W{111} surfaces, in contrast to the findings for He diffusion near W surfaces. Based on the H behavior obtained by our MD simulations, the time evolution of the concentration distribution of interstitial H atoms in a semi-infinite W single crystal irradiated by energetic H projectiles was calculated. The effect of H concentration on H diffusion is discussed, and the applicability of the diffusion coefficients obtained for dilute H in W is assessed.