Study on Fatigue Crack Growth Mechanism and Deformation-Induced Crystallization in a Zr-Based Bulk Amorphous Alloy
| Project/Area Number |
17560083
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | TOKYO UNIVERSITY OF SCIENCE |
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Principal Investigator |
NAKASONE Yosi TOKYO UNIVERSITY OF SCIENCE, Department of Engineering, Professor (10266918)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,640,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥240,000)
Fiscal Year 2007: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2006: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2005: ¥900,000 (Direct Cost: ¥900,000)
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| Keywords | Amorphous / Metallic Glass / Crystalization / X-ray Diffraction / Fatigue / Crack Growth / Striations / Crack Closure Phenomenon / き裂閉口 / Amorphous / Metallic Glass / Crystallization / X-ray Diffraction / Fatigue / Crack Growth / Striation / Crack Closure |
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| Research Abstract |
The present paper has investigated fatigue crack growth behavior and deformation-induced crystallization in a Zr-based bulk amorphous alloy. Fatigue crack growth tests were performed on center-cracked plate specimens of 55at%Zr-10at%Al-5at%Cu-30at%Ni having a length of 50mm, a width of 16mm and a thickness of 2mm at room temperature in air. Tension to tension fatigue loads were applied at stress ratios of R=0.05 to 0.3 at a loading frequency of 5Hz. The plastic replica technique was used for observing crack growth behavior. Crack branching, crack deflection and non-propagating branches often occurred at specimen surfaces of the amorphous alloy. Thus, the crack growth rate vs. stress intensity factor range diagrams in which projected crack length was used fluctuated widely. This anomalous growth behavior can be attributed to the fact that internal crack surfaces were very rough. Roughness-induced crack closure was observed at stress ratios lower than 0.3. Scanning electron microscopy revealed striation-like patterns in some portions of the rough crack surfaces.
Spot X-ray diffraction analysis (a focal diameter of 30 micrometer) of crack surfaces were also made and detected localized crystallization in the form of Zr2Cu. As has been reported by J.-J.Kim et al.in Science, vol.295 (2002), the localized crystallization may have been brought about by severe deformation in the vicinity of crack tips. The striation-like patterns were produced in some portions of crack surfaces so crystallized. Sparks were also observed emitted from crack peripheries by the high-speed camera.
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Report
(4 results)
Research Products
(84 results)
