View article

Fe‐S‐Si immiscibility has been investigated using in situ X‐ray methods at high pressure and high temperature. An in situ X‐ray diffraction study of immiscible liquids for P∼5 GPa and T/Tm∼1.1 has been performed, showing differences in structural properties between S‐rich and Si‐rich coexisting liquid phases. Moreover, the respective role of S and Si on Fe alloys has been quantitatively investigated in Fe‐X liquids (X = S, Si) with 20%wt of light elements. The transition from immiscible to miscible textures has been observed in the ternary mixture by in situ X‐ray radiography for the Fe‐18wt%S‐8.5wt%Si (Fe‐28.8at%Si‐11.9at%S) sample composition between 12 and 16 GPa. Closure of the miscibility gap occurs in the same pressure range as the Fe‐S eutectic liquid evolves toward a compact structure. By working within the framework of the hard sphere (HS) fluid commonly used in liquid state theory, we show …