PURPOSE: To enhance the corrosion resistance and the temperature characteristics without deteriorating the magnetic characteristics by a method wherein a mixture in the specific composition containing rare earth oxide is heat-treated and then washed away to remove any by-product of reaction.
CONSTITUTION: A mixture meeting the following requirements is prepared i.e. a material powder comprising respective powders such as rare earth element (Rem) oxide containing Y, ferroboron, boron oxide, iron, cobalt, nickel, ferrocobalt alloy, cobalt nickel alloy, ferronickel, iron oxide, cobalt oxide and nickel oxide is properly selected so that the mixture may contain Rem:8W30 at.%, B:2W20at.% with the residual parts substantially comprising Fe, Co, Ni subject to respective blended amount of Fe:10W75at.%, Co:7W50at.%, Ni:8W30at.% as well as (Fe+Co+Ni):50W90at.%. Then, metallic Ca or CaH2 is blended with the mixture to be heated in inert gas atmosphere up to 800W1200°C causing reduction.diffusion reaction and after being cooled down, a reaction product is washed away to remove any by-product of the reaction.
FUKUDA YASUTAKA
SHIMOTOMAI MICHIO
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