著者

安田 秀幸 野北 和宏

出版者

一般社団法人 軽金属学会

雑誌

軽金属 (ISSN:04515994)

巻号頁・発行日

vol.71, no.1, pp.22-29, 2021-01-15 (Released:2021-02-15)

参考文献数

35

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This paper proposes a technique for evaluating the nucleation sequence and grain refinement phenomena during solidification of a metallic alloy. Time-resolved and in-situ transmission imaging using a monochromatized X-ray in a synchrotron radiation facility, SPring-8, showed wave-like nucleation events, in which nucleation sequentially occurred along the temperature gradient, in an Al-4mass%Si alloy with addition of TiB2 (Al-3mass%Ti-1mass%B alloy). The position and time of nucleation events were measured to analyze the nucleation wave. The wave motion, which was calculated from the measured data, was used to evaluate the difference of nucleation temperature for each dendritic grain from the wave front. The standard deviation of the temperature difference in the Al-4mass%Si alloy with TiB2 particles was evaluated to be as small as 0.25 K. The addition of TiB2 reduced the standard deviation to more than one tenth. This study shows that the dispersion or the standard deviation is a representative figure for evaluating the potency of nuclei.

著者

杉山 明 安田 秀幸 柳楽 知也 吉矢 真人 上杉 健太朗 梅谷 啓二 大中 逸雄

出版者

公益社団法人 日本鋳造工学会

雑誌

鋳造工学 = Journal of Japan Foundry Engineering Society (ISSN:13420429)

巻号頁・発行日

vol.83, no.3, pp.131-136, 2011-03-25

参考文献数

11

被引用文献数

1

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It is well known that controlling the graphite shape in cast iron is a critical issue to achieve appropriate properties. It is of interest to know how the microstructure in cast iron evolves during solidification. So far, time-evolution of the microstructure has not been observed in-situ. This paper presents the in-situ observation results of cast iron solidification using X-ray imaging of synchrotron radiation. Transmission X-ray images with a spatial resolution of as small as 5<i>μ</i>m were obtained by an X-ray detector SATICON in an imaging beam line 20B2 at SPring-8. A 10 × 10 × 0.1mm specimen was melted and solidified in a mold made of Al₂O₃ placed in a vacuum chamber. The observation showed that the solidification started with austenite dendrites, after which the eutectic structure was formed. Graphite clusters of about 100<i>μ</i>m in diameter were formed in the remaining liquid surrounded by the eutectic structure at a cooling rate of less than 10K/min. At a cooling rate of 10K/min, the primary dendrite and the eutectic grains moved up and down, respectively, due to the bouncy force.

著者

杉山 明 前川 裕貴 後藤 耕太 山根 功士朗 安田 秀幸 吉矢 真人 柳楽 知也 牛込 智章 佐藤 彰洋 梅谷 啓二 上杉 健太朗

出版者

公益社団法人 日本鋳造工学会

雑誌

鋳造工学 全国講演大会講演概要集 第161回全国講演大会講演概要集 (ISSN:18805388)

巻号頁・発行日

pp.13, 2012 (Released:2017-03-01)

著者

上部 伊織 道原 健人 森下 浩平 柳楽 知也 安田 秀幸

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.103, no.12, pp.678-687, 2017 (Released:2017-11-30)

参考文献数

27

被引用文献数

5

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This study demonstrates in-situ measurement of solute partition coefficient in multicomponent alloys, using X-ray transmission imaging and X-ray florescence spectroscopy. The developed technique was applied to determine partition coefficients of Cr, Ni and Mo between δ phase and liquid phase in Fe-17.4Cr-12.6Ni-2.0Mo-1.6Mn-0.6Si alloys (mass%). In the observation and measurement, X-ray fluorescence spectra were directly obtained by irradiating the incident X-ray beam (23keV) to the solid phase or the liquid phase near solid/liquid interface. The partition coefficients were simply determined from the X-ray florescence analysis. In addition, successive measurements during unidirectional solidification allowed to measure change in partition coefficient along solidification path. During the solidification, partition coefficients of Cr, Ni and Mo changed from 1.01 to 1.08, from 0.76 to 0.70 and from 0.86 to 0.74, respectively. The present study proved that the developed technique was applicable to determine partition coefficients of 3d and 4d transition elements of which characteristic X-ray energies ranged from 4 to 20keV.