OS3-5
微⼩重⼒下における Fe-Cu 合⾦の相分離挙動
Phase Separation Phenomena of Liquid Fe-Cu Alloys
under the microgravity condition
正⽊匡彦 1, 村⽥駿１、武川⻯弥１,敷地駿 1, ⼩畠秀和２，織⽥裕久 3, ⼩⼭千尋 3，下⻄⾥奈 3，⽯川毅彦３,永⼭勝久１Tadahiko MASAKI1, Shun MURATA1, Tatsuya TAKEKAWA1, Shun Shikichi1, Hidekazu
KOBATAKE2 ,Hirohisa ODA3, Chihiro KOYAMA3, Rina SHIMONISHI3, Takehiko ISHIKAWA3 andKatsuhisa NAGAYAMA1
芝浦⼯業⼤学，Shibaura Institute of Technology#1,
同志社⼤学，Doshisya Univ.#2,2
宇宙航空研究開発機構，JAXA#3
121.

Introduction
Fe-Cu alloy is one of the popular peritectic alloys, which has a flat liquidus line around intermediateconcentration range. It is known that when this alloy around intermediate concentration is quenched fromliquid state, a macroscopic liquid phase separation occurs below the liquidus line. Recently, C. P. Wang et al.
found that a curious phase separation in atomized Fe-Cu spherical alloys which was formed co-axial multisphere. Nagayama also make Fe-Cu powders by using atomization with the use of a short drop tube, the same
shape of spherical sample was observed. This phase separation attracts interests, however, the mechanism
cannot be revealed because the measurement of the temperature measurement of small particle is quitedifficult. Recently, we applied the gas-jet levitation method for the observation of this phase separation. As
you know, the sample size of gas-jet levitation is around 2 mm which is sufficiently large for the temperature
measurement by pyrometers. Then we proposed to the observation of the phase separations under
microgravity condition due to the electrostatic levitation furnace, ELF, which is installed on the ISS.
Microgravity experiments were performed in last February and March and the cooling curves were obtained.
In this report, we show the quick review of our microgravity experiments and discuss the feature of coolingcurve.
2.

Experiments and Results

2.1. Micrigravity Experiments
For microgravity experiments with the use of ELF, spherical Fe-Cu alloys whose diameter were around 2mm
were prepared via the gas-jet levitator coupled with laser diodes. Concentrations of samples were Fe30Cu70,Fe40Cu60, Fe50Cu50, Fe60Cu40, Fe70Cu30 in atomic percent, those were covered the intermediate concentration
range of Fe-Cu alloys. Samples were installed in the sample holder of ELF and launched to the ISS. Samples
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were processed February 10th, February 17th and March 10th. The sample was levitated in the chamber of ELF
and heated by lasers. At the first experiment, the sample position was quite stable at the solid phase, however,it become unstable when the sample was melted. The heating process was adjusted our samples, we could
melt and solidify of sample successfully. The samples were retrieved last June, the observation of sample wasin progress. The detail of our experiments will be described by Takekawa in poster session.

2.2. Results and discussion
Figure 1 shows the typical cooling curve around the solidification temperature under microgravity condition.
A photo image of camera installed in the pyrometer was superimposed on the figure. Many of exothermic
signal were observed. We suspect that the first plateau was the signal of the solidification of Fe rich phase,

Figure 1. Typical cooling curve of Fe40Cu60 alloy at solidification.

which can be seen the time from 0.5 sec to 10 sec in figure 1. The second plateau which can be seen the timefrom 17 sec to 18 sec can be regarded as the signal of the solidification of Cu rich phase. Exothermic signals at
the time around 14 sec might be derived from solidification of small droplets or shells in the sample. The
analysis of inside the sample is in progress. The relation between features of alloy structure and these signals
will be revealed, which will be described by Takekawa in the poster session.
References
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3)

C. P. Wang, X. J. Liu, I. Ohnuma, R. Kainuma, K. Ishida, Science 297, 990(2002).
Y. Fujiwara, T.Masaki, Proceedings of JASMAC 33 (2021).

© 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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