Abstract
The 2-17 type rare earth permanent magnets show high coercivity only when they are subjected to aging after solution treatment. It is necessary for obtaining the high coercivity that they are in a single 1-7 phase region at the solution temperature. In the present study, an isothermal phase diagram in the Sm-Zr-Co ternary system at 1473 K close to the solution temperature was constructed, in order to investigate the extent of composition ranges stable for the 1-7 phase due to Zr addition, and the behavior of the Zr atom in the 1-7 phase was investigated. It is shown that the Zr addition may fairly extend the stable 1-7 phase region to the higher Co content. Zr atom dissolved in the 1-7 phase seems to substitute either a pair of Co atoms occupying a dumbbell site or a single Sm atom involved in the 1-7 phase.
