2005 Fiscal Year Final Research Report Summary
Quantitative analysis of ω-β phase transformation at 131 K enhanced by electron irradiation using a recent electron microscopy
| Project/Area Number |
16560583
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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 |
Physical properties of metals
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| Research Institution | Okayama University of Science |
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Principal Investigator |
SUKEDAI Eiichi Okayama University of Science, Mechanical Systems Engineering, Professor, 工学部, 教授 (00090217)
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| Project Period (FY) |
2004 – 2005
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| Keywords | Ti alloy / β-ω phase transformation / electron microscope / cooling experiment / radiation enhanced diffusion / life time / aging under stressing / ω-α phase transformation |
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| Research Abstract |
ω-phase transformation in β-Ti alloys occurs due to aging, stressing and cooling. Since appearance of ω-phase crystals affects physical properties of the alloys, the phase transformation has been investigated on the industrial viewpoint and to clarify the phase transformation mechanism.
In the present work, a collection of data for quantitative analysis of β-ω phase transformation behavior has been planned, because phase transformations have been applied for making intelligent materials and their precise controlling is important for the applications. The following two experiments have been carried out:
(1)Annihilation behavior of ahtermal ω-phase crystals, formed by cooling at 131 K was investigated under electron irradiations with four different conditions. The experiments have been carried out at 131 K using in-situ observation technique. The processes were recorded in TV-VTR system and starting and finishing times of annihilations were determined. Two different origins of annihilation
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s due to electron irradiation have been considered; temperature-rise and radiation enhanced diffusion. Theoretically estimated temperature-rise was less than 1 degree, but the estimation did not considered effects of contamination of specimen surface, which affects the temperature-rise, as mentioned in literatures. Since specimen surfaces are generally contaminated, it becomes a problem to consider effects of contamination.
(2)In β-Ti alloys, β-ω-α phase transformation sequence occurs. It was planned to clarify electron states of each phase using EELS technique for understanding the process quantitatively. A two-steps aging method was adopted to occur each process. In the second process, instead of ω-α phase transformation, ω to a new phase transformation occurs ; a new phase appears. The crystal structure of new phase has been investigated using electron diffraction pattern analysis and HREM method, but the structure has not been clarified.
The results obtained in the present work indicate that two problems exist prior to the quantitative analysis of β-ω-α phase transformation. Less
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