Absorption of Hydrogen Isotopes by Vanadium-based Low Activation Materials

钒基低活化材料对氢同位素的吸收

• 批准号: 14380218
• 负责人: WATANABE Kuniaki
• 金额: $ 5.12万
• 依托单位: Toyama University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14380218/
• 关键词: Fusion Reactor; Low-activation Materials; Vanadium Alloys; Hydrogen Isotopes; Blanket; Titanium; Surface; Permeation Barrier

Vanadium alloys are potential candidates of low activation structural materials for fusion reactors. Permeability of hydrogen isotopes including tritium, however, is high in these alloys. It is known that the permeation of hydrogen isotopes though group 5 metals sensitively depends on surface states, but the systematic study has not been carried out for these alloys. From this viewpoint, absorption of H_2 and D_2 by V-Ti and V-Ti-Cr alloys was examined in the present study in combination with surface analysis by X-ray photoelectron spectroscopy to understand the correlation between surface chemical states and the reaction rates of hydrogen isotopes.Sheet type specimens of V-4Ti alloy and V-4Ti-4Cr alloy supplied by the National Institute for Fusion Science were installed in an ultra-high vacuum chamber, and their surfaces were analyzed after heat treatments at 673-1273 K. Enrichment of Ti on the surfaces were clearly observed above 800 K for both alloys. The specimens with different surface Ti concentrations were prepared by respective heat treatments, and hydrogen absorption was examined in a temperature range from 523 to 1023 K. The sticking coefficient α on the surface without Ti enrichment was 10^<-3> -10^<-4>, while the surface segregation of Ti up to [Ti]/[V] 〜0.5 led to the reduction in α by 2-3 orders of magnitude. Namely, the surface segregation of Ti caused the barrier effect against hydrogen permeation. The potential barrier against dissociative adsorption of hydrogen evaluated by ab initio calculations showed that direct influence of Ti is negligibly small. It was concluded that the reduction in α was due to the increase in the surface coverage of impurity oxygen caused by the presence of Ti whose chemical affinity to oxygen is larger that of V. The isotope effect between H_2 and D_2 was small and not observable under the present conditions.

钒合金是聚变堆低活化结构材料的潜在候选者。然而，在这些合金中，包括氚的氢同位素的渗透性高。氢同位素在第5族金属中的渗透敏感地依赖于表面状态，但对这类合金的渗透还没有系统的研究。从这个观点来看，本文研究了V-Ti和V-Ti-Cr合金对H_2和D_2的吸收，并结合X射线光电子能谱表面分析，探讨了表面化学状态与氢同位素反应速率之间的关系。在高真空室中进行了热处理，并在673-1273 K进行了表面分析。两种合金在800 K以上的表面上都明显观察到Ti的富集。通过热处理制备了不同表面Ti含量的试样，并在523 ~ 1023 K温度范围内进行了吸氢实验。未富集Ti的表面粘附系数α为10^<-3>-10 ^<-4>，而当Ti的表面偏析达到[Ti]/[V]&lt;$0.5时，α降低了2-3个数量级。也就是说，Ti的表面偏析引起了对氢渗透的阻挡效应。对氢的解离吸附的势垒从头计算评估表明，钛的直接影响可以忽略不计的小。结果表明，α的降低是由于Ti的存在使杂质氧的表面覆盖率增加，Ti对氧的化学亲合力大于V。H_2和D_2之间的同位素效应很小，在本实验条件下观察不到。

项目成果

R.Hayakawa, Y.Hatano, A.Pisarev, K.Watanabe: "Barrier effect against hydrogen ingress by Ti segregating to surface of V-Ti alloy"Physica Scripta. (印刷中).

R.Hayakawa、Y.Hatano、A.Pisarev、K.Watanabe：“Ti 偏析到 V-Ti 合金表面对氢进入的阻挡效应”Physica Scripta（出版中）。

Barrier Effect against Hydrogen Ingress by Ti Segregating to Surface of V-Ti Alloy

Ti偏析到V-Ti合金表面对氢侵入的阻挡作用

• 发表时间: 2004
• 期刊: Physics Scripta T108
• 作者: R.Hayakawa;Y.Hatano;A.Pisarev;K.Watanabe
• 通讯作者: K.Watanabe

Surface Segregation of Ti in a V-4Cr-4Ti Alloy and Its Influence on the Surface Reaction Rates of Hydrogen Isotopes

• DOI: 10.2320/matertrans.46.511
• 发表时间: 2005-03
• 期刊: Materials Transactions
• 影响因子: 1.2
• 作者: Y. Hatano;R. Hayakawa;K. Nishino;S. Ikeno;T. Nagasaka;T. Muroga;Kuniaki Watanabe

R.Hayakawa, Y.Hatano, K.Fujii, K.Fukumoto, H.Matsui, K.Watanabe: "Surface Segregation and Oxidation of Ti in a V-Ti alloy"Journal of Nuclear Materials. 307-311. 580-584 (2002)

R.Hayakawa、Y.Hatano、K.Fujii、K.Fukumoto、H.Matsui、K.Watanabe：“V-Ti 合金中 Ti 的表面偏析和氧化”核材料杂志。

Surface segregation and oxidation of Ti in a V- Ti alloy

V-Ti合金中Ti的表面偏析和氧化

• 发表时间: 2002
• 期刊: Journal of Nuclear Materials 307-311
• 作者: Hattori;K.;R.Hayakawa 他
• 通讯作者: R.Hayakawa 他