| Project/Area Number |
03452247
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Physical properties of metals
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| Research Institution | Kyushu University |
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Principal Investigator |
OKI Kensuke Kyushu University, Graduate School of Engineering Sciences, Professor, 総合理工学研究科, 教授 (70037860)
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| Co-Investigator(Kenkyū-buntansha) |
ITAKURA Masaru Kyushu University, Graduate School of Engineering Sciences, Research Associate, 総合理工学研究科, 助手 (20203078)
MATSUMURA Syo Kyushu University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (60150520)
KUWANO Noriyuki Kyushu University, Graduate School of Engineering Sciences, Associate Professor, 総合理工学研究科, 助教授 (50038022)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥6,600,000 (Direct Cost: ¥6,600,000)
Fiscal Year 1992: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1991: ¥5,500,000 (Direct Cost: ¥5,500,000)
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| Keywords | order-disorder transformation / antiphase boundary / free energy / kinetic equation / cupper-platinum alloy / iron-silicon alloy / simulation / electron microscopy / 規則・不規則転移 / 相転移過程 / 鉄ーシリコン合金 / 銅ー白金合金 / 自由エネルギ- / 時間依存ギンツブルグ-ランダウモデル / 規則合金 / 長周期構造 |
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| Research Abstract |
The objective of the research is to clarify the behavior and the effects of antiphase boundaries on the order-disorder transformation process. The kinetic equation was formulated by developing a Ginzburg-Landau type expansion of the free energy in order to carry out simulation of the changes in antiphase boundary structures. From the simulations, the following results were drawn. (1) At T>T_c ( the critical temperature of ordering ), disordering undergoes by expansion of a disorder region which has formed on antiphase boundaries. (2) At T<T_c, antiphase boundaries can have unevenness on the surface where a pair of hairpins are formed. The transformation from L1_<2-s> ( long period antiphase superstructure ) to L1_2 proceeds by receding of the hairpins. (3) At a low temperature region, the surface energy of antiphase boundaries is relatively high so that antiphase boundaries tend to become flat. Therefore, periodic antiphase boundaries cannot move and then the L1_<2-s> becomes metastable.
Transmission electron microscopy (TEM) and X-ray diffraction experiments were performed to examine the effects of antiphase boundaries on the order-disorder transformation. In the specimen of Cu_3Pt with a small variant size of L1_<2-s>, periodic antiphase boundaries are reduced by the hairpin mechanism to transform L1_<2-s> to L1_2. In the specimen with a large variant size, on the other hand, the L1_<2-s> phase remains metastable. High resolution TEM observation showed that in an alloy of Fe-Si the thickness of "wetting" on antiphase boundaries increases with annealing time. The results of the simulations and experiments confirmed that antiphase boundaries give significantly important effects on the process of order-disorder transformation in alloys.
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