Specific features of solid HDDR in alloys based on SmCo5 in low-pressure hydrogen

The methods of differential thermal analysis and X-ray phase-diffraction analysis are used for the investigation of the interaction of an alloy based on the SmCo5 compound with hydrogen. The alloy is held in hydrogen for 2 and 5h under pressures of 200, 300, 400, and 500 kPa in the temperature range 473–1223°K. The interaction of the alloy with hydrogen at 973°K under the pressures {ie602-01}, 300, and 400 kPa leads to the transformation of the SmCo3 impurity phase into an unidentified phase or unidentified phases. As the hydrogen pressure rises to {ie602-02}, we observe the formation of a mixture of SmCo5 and SmHx and the appearance of the traces of γ-Sm2Co17. At 1223°K, for all levels of hydrogen pressure in the process of interaction, the compositions of the products of hydrogen-induced phase transformations are identical, namely, SmCo5, SmHx, and Sm2Co17. Moreover, for {ie602-03}, 400, and 500 kPa, we detect the traces of Co. It is shown that the amounts of samarium hydride and the Sm2Co17 phase increase with the pressure of hydrogen. It is shown that, as the time of holding under a pressure {ie602-04} increases to 5h, the degree of disproportionation of SmCo5 increases.