OR3-10In-situ 濃度観測点増加に伴う液体金属の拡散係数測定法の解析精度
Analysis Precision of Diffusion Measurementsin Liquid Metals through Increasing
In-situ Concentration Measurement Point
小林由央 1, 椎木政人 1,2, 正木匡彦 3, 鈴木進補 1,Yoshihiro KOBAYASHI1, Masato SHIINOKI1,2, Tadahiko MASAKI3 and Shinsuke SUZUKI1早稲田大学，Waseda University
ドイツ航空宇宙センター，Deutsches Zentrum für Luft- und Raumfahrt
3 芝浦工業大学，Shibaura Institute of Technology

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1. Introduction
Diffusion coefficients in liquid metals are important for understanding the solidification process inmetallic materials and the atomic transport in liquid metals. In-situ X-ray fluorescence analysis (in-situ XRF)
has been proposed as the diffusion measurements in liquid metals by measuring the concentration at only one
point in a capillary1). In this study, another X-ray device was installed additionally to double the number ofthe measurement points. In operating several X-ray devices without a collimator, the precision of theconcentration measurement would be declared by detecting an intensity from not intended point, such as
another measurement point. The objective of this study is to determine the effect of a collimator on an obtained
X-ray spectrum and the precision of the concentration measurement during operating two X-ray devices in insitu XRF.

Figure 1. Experimental apparatus of in-situ XRF.

2. Experimental Procedure
Figure 1 shows the experimental apparatus of in-situ XRF for diffusion experiments in liquid metals. Twosets of the X-ray sources (Mini-X2, Amptek Inc.) and the detectors (X-123SDD, Amptek Inc.) were containedin a shield box. The collimator was made of A2017.
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A pure Sn rod was cast into 1.5×1.5×10 mm3 and contained in the capillary, the size of which was
1.5×1.5×63 mm3. The capillary was heated to 573 K and then its temperature was maintained in vacuum. Theupper and lower X-ray sources were positioned at 40.0 mm and 7.2 mm above the bottom of the capillary,respectively. X-ray fluorescence was detected from each detection point with an integration time of 600 s byusing the upper detector, while operating only the upper X-ray source or both X-ray sources. By confirming
the effect of the collimator, the above measurements were performed with and without the collimator.
3. Results
Figure 2 shows the obtained X-ray spectra from the pure Sn rod. Without collimator, the intensity of Kαemission line of Sn (Sn Kα) detected by operating both X-ray sources was larger than that detected byoperating only the upper X-ray source. By adopting the collimator, the detected Sn Kα intensity did not change
significantly when both X-ray sources were operated or only the upper X-ray source was operated.

Figure 2. Obtained X-ray spectra from the pure Sn rod; (a) detected with no collimator, and (b) detectedwith the collimator. Black line: obtained spectrum by operating only the upper X-ray source.
Red line: obtained spectrum by operating both X-ray sources.

4. Discussion
According to Fig. 2(a), the intensities of Kα emission lines of Fe and Ni (Fe Kα and Ni Kα) were also
detected. This indicated that an X-ray intensity was detected from not only another measurement point, butalso the body of the furnace (made of Ni) and frame of the window (made of Fe) with no collimator. The
precision of the concentration measurement in in-situ XRF is declared due to these intensities, which isconsidered as the background in the spectrum. According to Fig. 2(b), an X-ray intensity from these materials
can be eliminated from the detected spectrum by adopting the collimator. Therefore, the precision of theconcentration measurement is maintained even though operating two X-ray sources in in-situ XRF.
5. Conclusion
By adopting the collimator, an intensity emitted from not intended point can be eliminated from theobtained X-ray spectrum. Therefore, the precision of the concentration measurement can be maintained when
operating two X-ray sources, as that when operating only one X-ray source.
Acknowledgement
This study was supported by the Japan Aerospace Exploration Agency (JAXA) Working group on“Diffusion Phenomena in Melts”, financial support by Kimura Foundry Co., Ltd., Grant-in-Aid for Scientific
Research(C) Grant Number JP23K04364, and Grant-in-Aid for JST SPRING, Grant Number JPMJSP2128.
References
1)

Y. Kobayashi, M. Shiinoki, R. Yamatake, T. Masaki and S. Suzuki: Int. J. Microgravity Sci. Appl., 38 (2021) 380302,DOI: 10.15011/jasma.38.380302.
© 2023 by the authors. Submitted for possible open access publication under theterms and conditions of the Creative Commons Attribution (CC BY) license(http://creativecommons.org/li censes/by/4.0/).
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