METALLIC MAGNETIC POWDER FOR MAGNETIC RECORDING AND PROCESS FOR PRODUCING THE METALLIC MAGNETIC POWDER

摘要

This invention provides a process for producing a metallic magnetic powder for magnetic recording, comprising, in sequence, the step of allowing a reducing agent to act on a metallic magnetic powder comprising particles having a metallic magnetic phase composed mainly of Fe or Fe and Co and containing one or more of rare earth elements (including Y), Al and Si (these elements being hereinafter referred to as "nonmagnetic components') in a liquid containing a complexing agent which can form a complex with at least one of the nonmagnetic components to elute the nonmagnetic components in the powder particles into the liquid (an elution treatment step), the step of heat treating the nonmagnetic component in a reducing gas atmosphere (a re-reduction treatment step), and the step of heat treating the nonmagnetic component in an oxidizing gas atmosphere (a stabilization treatment step). The production process can produce a metallic magnetic powder for magnetic recording, comprising particles having a particle length of 10 to 45 nm and an axial ratio of two or more, the tip part of the particles being rounded.