Effect of diffusion coefficient variation on interrelation between hydrogen diffusion and induced internal stress in hydrogen storage alloys
Effect of diffusion coefficient variation on interrelation between hydrogen diffusion and induced internal stress in hydrogen storage alloys
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DOI：
10.1016/j.jallcom.2016.08.288
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发表时间：
2017-01
影响因子：
6.2
通讯作者：
Kenta Goto;S. Ozaki;W. Nakao
中科院分区：
文献类型：
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作者：
Kenta Goto;S. Ozaki;W. Nakao
氢在储氢合金中的扩散行为不仅受氢浓度的影响，还受氢原子使合金晶格膨胀而产生的应力的影响。观察到了氢在应力作用下逆浓度梯度扩散的上行扩散。此外，即使在低氢浓度下，合金中氢的逸度也明显偏离1，从而降低了流量。本文利用有限元分析方法研究了应力和扩散系数随浓度的变化对低浓度氢扩散的影响。结果表明，考虑应力效应的变扩散系数模型比Fick扩散模型和等系数SID模型与实验结果吻合得更好。得出的结论是，即使浓度较低，也应考虑这种影响。
A diffusion behavior of hydrogen in a hydrogen storage alloy is affected by not only hydrogen concentration but also the stress induced by hydrogen atom expanding the lattice of the alloy. The uphill diffusion in which hydrogen diffused against the concentration gradient due to the stress has been observed. Moreover, the fugacity of hydrogen in the alloy deviates from unity significantly even at low hydrogen concentration, which decreases the flux.In this paper, the effect of the stress and the diffusion coefficient variation with the concentration on hydrogen diffusion at low concentration was investigated using the finite element analysis. As a result, the variable diffusion coefficient model combined with the stress effect showed better agreement with the experimental result than Fick's diffusion models and the constant coefficient SID model. It was concluded that the effect should be considered even if the concentration is low.