Hydrogen effect on the sigma-phase in Fe53.8Cr46.2

Investigation of the stability and properties of a sigma-phase type compound Fe53.8Cr46.2 after electrochemical hydrogen treatment was made using X-ray diffraction and 57Fe Mössbauer spectroscopy techniques. The amount of the hydrogen uptake was estimated to be equal to ∼1.2H per unit formula, and its presence leads to an anisotropic cell parameter expansion. However, the hydrogenated state appears as metastable with reference to the aged samples analyzed a few days to months after loading with hydrogen.