PURPOSE: To obtain an alloy magnetic powder whose grain-size distribution is uniform, which is branched little and whose oxidation-resistant property is excellent by a method wherein, in a magnetic alloy powder composed mainly of iron and cobalt, a BET specific surface area and an axial ratio are specified.
CONSTITUTION: In an iron-cobalt alloy magnetic powder, a hydroxide is coprecipitated by using a ferric salt and a cobalt salt; this coprecipitate is treated by using an autoclave. Regarding an alloy magnetic powder which has been obtained by heating and reducing an obtained cobalt-contained α-iron oxyhydroxide, its saturation magnetization amount is large, it has a structure which is not branched, its grain size distribution is uniform, its axial ratio is 4.5 to 6.0 and its BET-method specific surface area is 25 to 35m2/g. Thereby, it is possible to obtain the alloy magnetic powder whose oxidation-resistant property has been improved.
NAKAZUMI TETSUYA
KISHIMOTO MIKIO
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