Influence of Aluminum and Hydrogen on the Properties of Sm2Fe17

Abstract

Cast, homogenized, and hydrogenated alloys based on intermetallic compound Sm₂Fe₁₇ with replacement of iron by aluminum to concentrations of 8.9, 17.9, 26.8, and 35.8 at % Al are investigated by the methods of X-ray fluorescence, X-ray diffraction analysis, and scanning electron microscopy. The alloys are hydrogenated at a temperature of 180°C and a pressure of 25–30 atm. It is established that all the hydrides of the nominal compositions Sm₂Fe_14.9Al_2.1H_3.6, Sm₂Fe_13.3Al_3.8H_2.1, Sm₂Fe_10.7Al_6.3Н₂, and Sm₂Fe_9.9Al_7.1H_1.8, like Sm₂Fe₁₇, are crystallized in the rhombohedral Th₂Zn₁₇ type of structure (space group R\(\overline{3}\)m). The partial replacement of Fe in Sm₂Fe₁₇ by Al is accompanied by a monotonic increase in the lattice periods and a simultaneous decrease in the specific saturation magnetization of the studied alloys. A similar trend is also established for the hydride phases.