Interaction between Hydrogen and Ground SmCo5 Alloy

The paper determines the phase composition of the ground KS37 alloy after conventional and solid hydrogenation and disproportionation (SmCo5 being the main phase and Sm2Co7 the impurity phase) at a hydrogen pressure of 0.1–0.4 MPa and at temperatures up to 950°C for 5 h. It is established that products resulting from grinding of the Sm2Co7 phase interact with hydrogen to 560°C to form Sm5Co19 and unidentified phases. The SmCo5 phase disproportionates in the temperature range 560–650°C and pressure range 0.1–0.4 MPa for 2 h. Recombination at 650–950°C leads to the SmCo5, Sm2Co7, and Sm2Co17 phases. The SmCo5 content of the recombined alloy is the highest at 950°C. It is shown that grinding in hydrogen prior to hydrogenation, disproportionation, desorption, and recombination accelerates the disproportionation reaction owing to the formation of defects during grinding. The high-temperature recombination of the SmCo5 phase in hydrogen is confirmed.