2015 Fiscal Year Research-status Report
Dynamic fracture toughness of tungsten under ternary loading
| Project/Area Number |
26820397
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| Research Institution | Osaka University |
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Principal Investigator |
Lee Heun Tae 大阪大学, 工学(系)研究科(研究院), 助教 (90643297)
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| Project Period (FY) |
2014-04-01 – 2017-03-31
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| Keywords | Tungsten / Laser ablation / In-situ experiments / Acoustic emission / Fracture toughness / Radiation damage / Hydrogen / Helium |
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| Outline of Annual Research Achievements |
H27 focused on characterising (A) the binary loading effect of radiation damage and hydrogen and (B) the effects of near surface He implantation on bcc metals W and Fe (F82H). With respect to (A) the following was achieved: 1. Mechanical properties of single crystal samples of orientation [100] and [110] with radiation damage introduced up to 1 dpa using MeV W-ions was characterised (Elastic properties and Resonant vibration frequencies). 2. In-situ hydrogen loading experiments was successful with setup of ion beam and faraday cup, as well as actualisation of in-situ H loading experiments. 3. Method of introducing artificial cracks was refined to produce semi-reproducible crack initiation sites. 4. Numerical model was setup to evaluate crack propagation behaviour in experimental geometry. 5. Single crystal tungsten samples [100] and [110] was procured, and due to their late arrival will be shipped out in May to IPP, Germany for radiation damage up to 1 MeV for ternary experiments in H28. 6. Means to benchmark laser vibrometer measurements with another analysis method (nano indentation) was achieved to improve confidence in the method. With respect to (B) other experimental devices were used to understand the the effect of helium on hydrogen retention behaviour and hydrogen ion reflection yields from Fe(F82H) and W, respectively. These provide important basic insight into the mechanisms of hydrogen-helium-radiation damage. The works related to this thrust was presented at international conference PFMC 15, and published as two papers.
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| Current Status of Research Progress |
Current Status of Research Progress
4: Progress in research has been delayed.
Reason
The research purpose is to evaluate whether brittle failure of tungsten is promoted under hydrogen, helium, and radiation damage. To achieve this purpose, in H27,binary loading experiments (hydrogen and radiation damage) was performed. However, significant experimental challenges were present: (1) Reproducible sample preparation to produce reproducible crack initiation sites was challenging. (2) The in-situ loading of Hydrogen suffered from poor ion gun performance (low flux, and unsteady source operation). (3) The data analysis of the complicated spectra measured required advanced programming and statistical analysis tools that had to be automated to increase the statistics. Due the above reasons, a statistically meaningful determination of change in fracture toughness under binary loading was not achieved. This will directly delay the H28 plans where ternary loading effects was to be determined. In addition, due to the late arrival of samples ordered in H27, the samples for experiments in H28 containing radiation damage (performed at IPP, Germany) will be shipped out later in May. Although the primary thrust has been delayed due to the above reasons, the secondary thrusts in characterising He-H-radiation damage effects employing other devices have proceeded much faster than planned as evidenced by two published papers.
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| Strategy for Future Research Activity |
The research plan is broken into the following sub tasks: 1. Determining the change in materials constants by H/He and H/He/damage loading - The effect of H and He on the material constants determined. 2. Determining the fracture toughness of W under binary and ternary loading - The fracture toughness is determined by numerical modeling and inputs from experiments. 3. Characterization of ternary (He-implanted and damaged) samples 4. Continuation of basic studies on hydrogen, helium, and irradiation damage studies in W and Fe (F82H) using other devices 5. Presentation of H27 results at international conference (5th International Symposium on Laser Ultrasonics and Advanced Sensing) in Linz, Austria is planned.
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| Causes of Carryover |
Due to the delay in the experimental progress as outlined in previous section, funds reserved for perishable goods (約9万円）was not used.
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| Expenditure Plan for Carryover Budget |
The funds will be used for travel expense and registration fees to attend international conference to support the dissemination/presentation of the research as well as obtaining up-to-date information on the state of the research field.
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[Journal Article] Reflection properties of hydrogen ions at helium irradiated tungsten surfaces2016
Author(s)
K Doi, Y Tawada, HT Lee, S Kato, N Tanaka, M Sasao, M Kisaki, M Nishiura, Y Matsumoto, T Kenmotsu, M Wada, Y Ueda, H Yamaoka
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Journal Title
Physica Scripta
Volume: T167
Pages: 014044
DOI
Peer Reviewed / Int'l Joint Research
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