Repulsive Nature for Hydrogen Incorporation to Fe_3C up to 14 GPa

摘要

We have performed in situ X-ray diffraction measurements under high pressure and high temperature to study hydrogen solubility in Fe_3C carbide. Hydrogen solubility can be estimated from a volume expansion associated with hydrogen incorporation into metal. The lattice volumes and phase relations of Fe_3C-H system and Fe_3C were measured up to 14 GPa and 1 973 K. The lattice volumes of Fe_3C measured in this study are well fitted using the 3rd order Birch-Mumaghan equation of state with the reported elastic parameters of Fe_3C. Obtained lattice volumes of Fe_3C-H are quite consistent with those of Fe_3C. No difference between the melting temperatures of Fe_3C-H and Fe_3C was observed. These results demonstrate that hydrogen incorporation into Fe_3C does not occur and hydrogen is unlikely to coexist with carbon in iron-alloy up to 14 GPa.