Increasing coercive field strength of permanent magnets - based on cobalt-rare earth(s) by tempering after sintering

摘要

The coercive field strength of sintered magnets based on Co5R alloys, where R is a rare-earth element or a mixt. of several rare-earth elements, is raised by tempering the magnets at 200-500 degrees C after sintering. After sintering the magnets are pref. cooled from 950-750 degrees C at 75 degrees C/min. prior to the tempering. Process raises the coercive field strength by about 50% cf. the value obtd. after sintering. In many cases the remanence and the energy prod. are also improved.