Hydrogenation, disproportionation, desorption, and recombination in the [Sm.sub.2][Co.sub.17-x][Fe.sub.x]-[H.sub.2] system. x-ray diffraction

Differential thermal analysis and X-ray diffraction are used to study phase transitions in the [Sm.sub.2][Co.sub.17-x][Fe.sub.x]-[H.sub.2] system (x = 3.9 and 5.95) during conventional and solid HDDR at hydrogen pressure 0.57-4.0 MPa and temperature up to 950°C. The ferromagnetic phase with [Th.sub.2][Zn.sub.17] structure disproportionates into Sm[H.sub.2 ± ], cobalt, and intermetallic FeCo after one-hour interaction with hydrogen at 1.1 and 0.6MPa and 700°C with x = 3.9 and 5.95. Recombination in vacuum at 770-950°C leads to a two-phase alloy consisting of the [Th.sub.2][Zn.sub.17]-type phase and intermetallic FeCo. Keywords: hydrogenation, disproportionation, desorption, recombination; samarium-cobalt alloys; two-phase ferromagnetic materials.