2014 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 | Laser ablation / Hydrogen embrittlement / Tungsten / Acoustic emission / Ion damage(Germany) / Fracture toughness |
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| Outline of Annual Research Achievements |
The following was achieved in H26: 1. The recoil force (load) was determined as function of laser input energy incident on tungsten (W) surface. 2. Difference in resonant vibration frequency of Hydrogen implanted and un-implanted samples was compared. 3. Acoustic emission arising from crack propagation from an artificially introduced crack was detected. 4. Single crystal samples of orientation [100] and [110] were shipped to IPP, Germany and radiation damage introduced up to 1 dpa using MeV W-ions. 5. Sample holder for in-situ experiments was purchased which allowed vacuum experiments for the research achievements (1)-(3).
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
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 H26, in vacuo experimental setup, method, and data analysis was established. The force generating laser source was characterized. Acoustic emission signal when a crack propagated was detected allowing for experimental determination of force vs crack propagation - a first step for determining fracture toughness. The change in material elastic properties due to hydrogen-only implantation was experimentally measured, establishing the baseline for binary and ternary experiments. For preparation of binary experiments (hydrogen and damage) in H27, samples were shipped to IPP, Germany and displacement damage of 1 dpa was performed.
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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/damage loading - The effect of H on the material constants is now determined for samples that have been pre-implanted with He or damage from H26. 2. Determining the fracture toughness of W under binary loading - The fracture toughness is determined by numerical modeling and inputs from experiments. 3. Preparation and characterization of ternary (He-implanted and damaged) samples - Samples are prepared for ternary experiments at IPP, Germany. 4. Presentation of H26 results (Experimental method and H-loading only results) at international conference (ICFRM 17) in Aachen, Germany is planned.
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