Stability of chromium-iron-cobalt permanent magnet alloys

About three years ago, Kaneko et.al described a new permanent magnet alloy system Based on the elements Cr, Fe and Co. Permanent magnets Based on this system can reproduce the properties of many of the alloys of the Al-Ni-Co system. The present work was undertaken to ascertain whether this similarity extended to temperature stability. Alloys of Cr-Fe-Co, including some with additions of Ti,Mo,V or Si were given the heat treatment necessary to produce optimum permanent magnet properties. Tests made on these magnets included measurements of the reversible temperature coefficient around room temperature, variation of coercivity with temperature, the reversible and irreversible magnetic changes up to 500°C. Metallurgical changes at still higher temperatures were also investigated. The Cr-Fe-Co magnets were found to behave very similarly to those of the Al-Ni-Co system and can, therefore, be developed for applications requiring a low temperature coefficient and good performance at high temperatures.