Quantitative determination of short-range order in magnetostrictive Fe-12.5 at. % Ga alloy single crystals

FeGa alloys are an important class of magnetostrictive materials for use in actuators and sensors. Quantitative determination of short-range order is critical for a fundamental understanding of the correlation of thermal history with magnetostriction in these and other alpha-Fe based alloys. This paper presents quantitative assessments of short-range order (SRO) from the diffuse peaks in the high-resolution x-ray diffraction scan data of as-grown and high-temperature annealed Fe-12.5 at. % Ga alloy single crystals. The peak analyzed was the diffuse peak in the forbidden (100) peak region of the diffraction pattern of bcc Fe-12.5 at. % Ga alloy single crystals. The [001]-oriented Fe-12.5 at. % Ga alloy single crystals were obtained using the vertical Bridgman technique. To quantitatively assess SRO in these alloy single crystals, the x-ray scattering intensities obtained were converted to absolute intensity in electron scattering units. To do this, reference scans were performed on a fully dense polystyrene sample. A Python language based code was used for the analysis of short-range order, and the values for the SRO coefficients up to the seventh shell were determined. These values agree with the type of ordering indicated by (111) scans of these crystals.