| 研究実績の概要 |
In this project, the development of Fe-Al alloys, particularly, the Al-added stainless steels, is focused on from the viewpoint of anomalous interaction behavior between Fe and Al atoms. The B2-structured FeAl is a good candidate for studying the atomic interaction. In this study, the point defect structure of Fe-rich B2-type FeAl has been analyzed based on its ordering behavior. Ordering parameter was investigated by the combination of in situ high-temperature XRD measurements and high-angle annular dark-field (HAADF)-scanning transmission electron microscope (STEM) techniques. According the XRD spectra, the long-range order parameter of Fe-rich B2-type FeAl was found to increase slightly with increasing temperature in an intermediate temperature range. In the HAADF-STEM images, the ordering behavior was evaluated from the intensity ratio between Fe and Al atomic columns. The intensity ratio was found to slightly increase with increasing quenching temperature, indicating the increase of ordering parameter with increasing temperature. The positive temperature dependence of the ordering parameter is thought to be caused by the re-ordering process, where anti-site Fe atoms tend to return to their right sublattice sites and Al-vacancies generate. In next stage, the ternary system composed of Fe atoms, Al atoms and vacancies will be further focused on. This will be informative for the design and development of Al-added stainless steels.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
In this year, the ordering behavior and point defect structure of Fe-rich B2-type FeAl was studied, as it was planed. In-situ high-temperature XRD and HAADF-STEM techniques were applied to analyze the ordering behavior. Positive temperature dependence of ordering parameter was found through these two methods. This should be of great help for understanding the atomic interaction between Fe and Al.
In addition, I have made oral presentation in two international academic conferences and two domestic academic conferences in this year. These conferences provided me with good opportunities to show my research results and to discuss with professors and specialists all over the worlds. Through the communication, I improved my research idea and made progress gradually.
Besides, I have successfully finished my doctoral dissertation and been awarded the doctoral degree.
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| 今後の研究の推進方策 |
In next stage, the ordering behavior in B2-type FeAl and the atomic interaction between Fe and Al atoms will be further studied at atomic level. One of the interesting and reasonable ideal is to regard the Fe-rich B2-type FeA as a ternary system rather than a binary one. This ternary system is composed of Fe atoms, Al atoms and vacancies. In order to analyze the ordering structure of these three "elements", HAADF-STEM techniques will be further used because this method is an effective way to observe the material at atomic level. The intensities of atomic columns in the HAADF images can provide information concerning the site occupancy. By analyzing the ordering behavior and defect structure, we can make better understanding of the anomalous atomic interaction between Fe and Al. This will be informative for the design and development of Al-added stainless steels.
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