Hydrogenation-disproportionation in samarium-cobalt ferromagnetic alloys based on Sm2 (Co, Fe, Cu, Zr)17

By methods of differential thermal analysis and X-ray phase analysis, we investigate the processes of hydrogenation, disproportionation, desorption, and recombination and solid hydrogenation, disproportionation, desorption, and recombination in Sm18.6Co46.1Fe27.1Cu5.9Zr2.3 commercial ferromagnetic alloy in the temperature range 293-1175 K and in the pressure interval from 5 to 4 MPa. By the method of differential thermal analysis, in the interval 293-1175 K, we recorded phase transformations at 680 K (formation of hydride), 937 K (disproportionation), and 1034 K. Desorption-recombination takes place in four stages with maximum hydrogen release at 405, 640, 724-840, and 900 K. Conventional hydrogenation-disproportionation results in formation of samarium hydride, solid solution of cobalt-iron, and an unidentified phase. In the case of solid hydrogenation-disproportionation, we detected another unidentified phase showing itself only in one peak. We performed phase analysis of the intermediate products of interaction. Desorption-recombination leads to renewal of the main initial phase, and heating of the alloy in hydrogen under initial pressure 0.1 MPa results in homogenization of the material.