A kinetic evaluation of the disproportionation reaction in Sm–Fe-based materials

Abstract The HDDR process for the production of permanent magnets was evaluated from the kinetic point of view. The disproportionation reaction was monitored using a modified VSM that enabled us to follow the progress of the reaction in a hydrogen atmosphere under isothermal conditions. The behaviour in hydrogen was evaluated for two different Sm–Fe-based alloys (Sm13.7Fe86.3 and Sm13.8Fe82.2Ta4.0). The disproportionation behaviour differs depending on the alloy composition. Whereas in the binary alloy the behaviour can be described with the sigmoid rate equation, the disproportionation of the ternary alloy suggests that the process is decelerated in its nature.