Figure 2. X-ray diffraction spectra before and after melting.

They were collected at 2,160 K (a), 1,810 K (b) and 1,690 K (c) during heating at 31 GPa. The starting material was composed of Fe (ɛ or γ) and Fe₃C (c), and the peaks of Al₂O₃ (a) were from a thermal insulator. The coexistence of ɛ- and γ-Fe phases at 1,610 K was due to a sluggish solid–solid phase transition49 and the peaks from the ɛ-phase were lost at 1,810 K. All sample peaks disappeared between 1,810 and 2,160 K. In addition, the background was enhanced slightly, indicating a diffuse scattering signal from a liquid sample.