Features of the HDDR process in alloys based on the SmCo5 compound

Abstract

The hydrogenation, disproportionation, desorption, recombination (HDDR) and solid-HDDR processes in the KC37 commercial ferromagnetic alloy (based on the SmCo5 compound) were studied in the temperature range 293–1215K and pressure range from 5×10−3Pa to 5MPa. This was carried out by means of differential thermal analysis (DTA) and X-ray diffraction analysis methods. During heating of the alloy under initial hydrogen pressures of 3–5MPa, we observed four effects: the formation of hydride at 295–323K, transformation of the SmCo3 impurity phase at 363–383K, decomposition of the hydride of the initial phase at 605–640K and its disproportionation at 850–858K. The desorption, recombination (DR) occurs with hydrogen desorption in two stages at 493 and 910K. The conventional hydrogenation, disproportionation (HD) of two-phase initial alloy results in the formation of samarium hydride and precipitation of cobalt. In the case of solid-HD an unknown phase was revealed in addition to samarium hydride and cobalt. A mixture of SmHx and Sm2Co17Hx hydrides was revealed after holding for 80min at 1160K during solid-HD. DR in both the conventional and the solid-HDDR results in homogenization of the alloy.