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Page 6 of 25 Park et al. J Mater Inf 2023;3:5 https://dx.doi.org/10.20517/jmi.2022.37

only a minor amount of heat would be exchanged. Hence, pre-trials were carried out to identify proper
parameters for achieving a sufficient resolution in the DSC signal. Alloys I and V were selected to optimize
the DSC settings. The chemical analysis (X = 0.365 and X = 0.727) are close to the composition limit of
Sn
Sn
the miscibility gap (X = 0.31-0.81) with the smallest Liquid + Liquid two-phase region. Therefore, the
Sn
1
2
maximum change of ∆H per time (t = ∆T/HR) was expected to intensify the signal. The defined time-
temperature profiles are graphically shown in Figure 3. Samples of alloys I and V with different masses (200
mg and 400 mg) were heated up at 30 °C min to 400 °C and held isothermally for 15 min to activate the Zr
-1
getter. Then, three different DSC settings were tested for each alloy to determine the actual phase
transformations of interest: (i) sample mass of 200 mg with the most commonly applied HR of 10 °C
min -1[48] ; (ii) sample mass of 200 mg with increased HR of 20 °C min ; and (iii) sample mass of 400 mg with
-1
-1
HR of 20 °C min . In the first time-temperature cycle, the samples were pre-melted at the respective HR to
a final temperature of 1,500 °C to guarantee perfect contact between the sample droplet surface and the
-1
alumina crucible for the second cycle. Subsequently, the samples were cooled to 450 °C at -30 °C min and
reheated to 1,500 °C with the defined HR to record the transition temperatures.
After the pre-trials, the actual DSC measurements for all samples I-V were based on the most proper
experimental parameters, and analyzed in detail within the Section “RESULTS OF EXPERIMENTAL
INVESTIGATIONS”.

Electromagnetic levitation technique
[50]
A previous study reported that the metastable miscibility gap in Cu-Co-Fe liquid alloys could be
measured using the electromagnetic levitation technique upon undercooling. The experiment was
conducted to confirm the liquidus, solidus, and metastable-liquid separation temperature in Ar/He (g)
atmosphere. Ar (g) was provided for the inert atmosphere, and He (g) was added to increase the thermal
conductivity attributed to its low atomic weight. They observed a temperature change over time and
confirmed the peritectic temperature, liquidus temperature, and metastable-liquid separation temperature.
This study demonstrated that the slope change from the time-temperature profile could represent the phase
transformation temperature of the alloys. In the present study, this technique was employed to measure the
miscibility gap in the Fe-Sn binary liquid using electromagnetic levitation equipment.

0.6 g of Fe-Sn alloy sample were charged in an alumina crucible (outer diameter: 8 mm × inner diameter 4
mm × height 10 mm) and placed inside the fused silica sample holder. A reaction chamber made up of a
fused silica tube was permanently purged by purified Ar(g). Ar(g) was purified by passing silica gel and
drierite® for moisture and ascarite® for a trace of CO (g). The flow rate was controlled by Mass Flow
2
Controller (KOFLOC, KOFLOC 3660, Kyoto, Japan). The MFC was preliminarily calibrated using a soap-
bubble-column technique. The melting procedure was the same as that described in Section “Sample
preparation” (also see Figure 2). The RF generator was turned on a current at 97 A under an Ar(g) flow rate
of 1.2 L min . As soon as the RF generator power was turned on, the sample was immediately levitated and
-1
melted. After the time-temperature profile showed a steady state, the injection of Ar(g) was replaced by a
-1
subsequent injection of He(g) at a rate of 2 L min . At the same time, the current of the RF generator was
controlled to cool down the sample to observe the slope change of the profile. When the sample was cooled
down and showed a steady state, the RF generator was turned off. The time-temperature profile during each
measurement was recorded by a PC connected to the pyrometer.

Contact angle measurement
Min et al. measured the contact angle change upon cooling of Bi-Cu-Sn liquid alloys using the
[51]
constrained drop method and showed that this technique was capable of detecting the binodal temperature
of the alloys that separated into two liquid phases. They confirmed that the contact angle was sensitive to