Role of iron for hydrogen absorption mechanism in zirconium alloys

Kazuo Kakiuchi, Noboru Itagaki, Takemi Furuya, Akihiro Miyazaki, Yoshiaki Ishii, Shunichi Suzuki, Takayuki Terai, Michio Yamawaki, P. Barberis, Komal Kapoor, Y. S. Kim, A. Motta, Brian Cox, L. Hallstadius, N. Ramasubramanian

Research output: Chapter in Book/Report/Conference proceedingConference contribution

19 Scopus citations

Abstract

The latest PIE results of Zry-2 and HiFi alloy (0.4%Fe-Zry2) showed that iron addition reduces the hydrogen pick-up ratio. In order to clarify this lower hydrogen absorption mechanism, three types of experiments were carried out for both alloys: (1) Measurements of the hydrogen pick-up ratio in the pre-transition region using an autoclave. (2) CPD (Contact Potential Difference) and FBP (Flat-band Potential) measurements of oxide film using a High Temperature Kelvin system and Photocurrent system. (3) Investigation of hydrogen absorption properties by Sieverts system and corrosion properties by autoclave for intermetallic compounds simulating SPP's Fe/Cr and Fe/Ni ratio in Zry-2 and HiFi. Autoclave tests showed that the corrosion behaviors of both alloys were similar. However, the hydrogen pick-up ratio depended on not only iron addition but also surface treatment (with and without pickling). Iron addition and non-pickling (as-received) reduced the hydrogen pick-up ratio. ΔCPD and FBP shifted to the positive side as the result of iron addition, and FBP changed with and without pickling. This difference in surface potential might be caused by the existence of anion vacancy concentration in the oxide film and furthermore may affect the electrochemical potential gradient over the oxide film. This potential gradient might control the proton diffusion in the oxide film. In the results of the hydrogen absorption tests on intermetallic compounds, Zr(Fe,Cr)2 with a higher Fe/Cr ratio showed lower hydrogen absorption, and Zr2(Fe,Ni) showed higher hydrogen absorption than Zr(Fe,Cr)2. In the results of corrosion tests on intermetallic compounds, Zr2(Fe,Ni) showed a much larger corrosion rate than Zr(Fe,Cr)2. It is considered that Zr2(Fe,Ni)-type precipitate might be oxidized easily in the oxide film, thus it might not contribute to the window for hydrogen absorption, and Zr(Fe,Cr)2 with a higher Fe/Cr ratio would reduce the amount of hydrogen penetrating through SPP at the oxide/metal interface. Based on these results, a tentative hydrogen absorption mechanism is proposed, explaining both roles of the electrochemical potential gradient over oxide film and the SPP window for the hydrogen absorption.

Original languageEnglish (US)
Title of host publicationZirconium in the NUCLEAR INDUSTRY - Fourteenth International Symposium
PublisherAmerican Society for Testing and Materials
Pages349-366
Number of pages18
Edition1467
ISBN (Print)0803134932, 9780803134935
StatePublished - Jan 1 2005
Event14th International Symposium on Zirconium in the NUCLEAR INDUSTRY - Stockholm, Sweden
Duration: Jun 13 2004Jun 17 2004

Publication series

NameASTM Special Technical Publication
Number1467
ISSN (Print)0066-0558

Other

Other14th International Symposium on Zirconium in the NUCLEAR INDUSTRY
CountrySweden
CityStockholm
Period6/13/046/17/04

All Science Journal Classification (ASJC) codes

  • Engineering(all)

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    Kakiuchi, K., Itagaki, N., Furuya, T., Miyazaki, A., Ishii, Y., Suzuki, S., Terai, T., Yamawaki, M., Barberis, P., Kapoor, K., Kim, Y. S., Motta, A., Cox, B., Hallstadius, L., & Ramasubramanian, N. (2005). Role of iron for hydrogen absorption mechanism in zirconium alloys. In Zirconium in the NUCLEAR INDUSTRY - Fourteenth International Symposium (1467 ed., pp. 349-366). (ASTM Special Technical Publication; No. 1467). American Society for Testing and Materials.