Development of isotropic Fe-Cr-Co-Mo based hard magnets

In the present work, we describe the development of isotropic hard magnets produced by isothermal aging process. The studied alloy compositions are Fe-30Cr-16Co-3Mo and Fe-30Cr-16Co-3Mo- 1.5Ti (wt%). The thermal conditions under which the alloys have attained the optimum magnetic properties and microstructures have been established. The Fe-30Cr-16Co-3Mo-1.5Ti (wt%) alloys have produced maximum coercive force, H/sub c/ = 800Oe remanence, B/sub r/ = 6.3kG. and energy product, (BH)/sub max/ = 2.9 MGOe. The coercivity of this alloy is better than those of known alloys with isotropic crystalline structure containing the 15-20wt% cobalt. The better coercivity in the studied alloys is resulted due to the optimization of heat-treatment conditions along with favorable microstructure. The microstructures of the studied alloys are free of undesirable non-magnetic gamma or sigma phases that influence the magnetic properties in the Fe-Cr-Co system alloys. (author)