1997 Fiscal Year Final Research Report Summary
Order-Disorder Transformation Processes with Composition Variations Studied by IKL-ALCHEMI-EDX Method
| Project/Area Number |
08455293
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | KYUSHU UNIVERSITY |
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Principal Investigator |
OKI Kensuke KYUSHU UNIVERSITY,Interdisciplinaary Graduate School of Engineering Sciences, Professor, 大学院・総合理工学研究科, 教授 (70037860)
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| Co-Investigator(Kenkyū-buntansha) |
HATA Satoshi KYUSHU UNIVERSITY,Interdisciplinary Graduate School of Engineering Sciences, Res, 大学院・総合理工学研究科, 助手 (60264107)
ITAKURA Masaru KYUSHU UNIVERSITY,Interdisciplinary Graduate School of Engineering Sciences, Res, 大学院・総合理工学研究科, 助手 (20203078)
KUWANO Noriyuki KYUSHU UNIVERSITY,Interdisciplinary Graduate School of Engineering Sciences, Ass, 大学院・総合理工学研究科, 助教授 (50038022)
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| Project Period (FY) |
1996 – 1997
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| Keywords | L1_0-type ordered state / Ti-Al-Mo ternary alloy / IKL-ALCHEMI-EDX method / site-preference of Mo / cluster variation method / Lennard-Jones potential / B2-type ordered state / dynamical diffraction effect |
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| Research Abstract |
The L1_0-type ordered state in Ti-Al-Mo alloys was investigated quantitatively by means of the IKL-ALCHEMI-EDX method (intersecting Kikuchi-line method ; IKL,atom location by channelling-enhanced microanalysis ; ALCHEMI,and energy dispersive X-ray spectroscopy ; EDX) using an analycal transmission electron microscope (TEM). The application of the IKL-ALCHEMI-EDX method to the B2-type ordered state was also examined. The main conclusions are drawn as follows.
1.The site-preference of Mo in an L1_0 ordered Ti-Al-Mo phase is fixed by concentration ratio of Ti : Al in the fcc matrix. Mo atoms tend to occupy Al sublattice sites for a Ti-enriched matrix, while the site-preference of Mo turns to Ti sublattice sites for an Al-enriched matrix. This indicates that Mo exhibits no significant ordering tendency with Ti or Al for the L1_0 ordered state.
2.The L1_0 ordered state in the Ti-Al-Mo system calculated by the cluster variation method (CVM) with the Lennard-Jones atomic potential [Abe et al. (
… More
1993)] indicates a preferential ordering tendency in Mo-Ti. The results of the CVM contradicts the present experimental results.It is considered that the atomic potential used in the CVM calculation should be estimated more strictly for analyzing the Ti-Al-Mo system.
3.The values of structure factors of L1_0 or B2 superlattice reflections in the Ti-Al-Mo system are so small that values of separation of Kikuchi-lines hardly change with degree of order. Some other methods using, for example, thickness fringes in dark field TEM images should be utilized with the IKL method to obtain more reliable values of degree of order.
4.The superlattice reflections for the B2-type ordered state in Ti-Al-Mo alloys are hardly observed for X-ray diffraction, but they often appear clearly for electron diffraction. Many-beam dynamical diffraction calculations rationalized that the appearance of B2 superlattice reflections in the electron diffraction patterns is due to strong dynamical diffraction effects of electrons. This suggests that the B2 ordered state in the Ti-Al-Mo system can be analyzed quantitatively by the IKL-ALCHEMI-EDX method. Less
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