| 简介 |
PROBLEM TO BE SOLVED : To provide ferromagnetic powder for a coated magnetic recording medium capable of forming a magnetic layer which is suitable for high density recording. SOLUTION : This ferromagnetic powder whose constituent body is iron containing Co : over 5-50 at.%, Al : 0.1-30 at.%, rare earth elements (including Y) : 0.1-10 at.%, element of the 2a group of a periodic table : less than 0.1 wt.% (including 0 wt.%) is composed of the flat needle-like particles 1 of an average long axis length : 0.01-0.40 μm and an X-ray crystal grain size (Dx) : 50-250 angstroms for which a short axis cross section 2 cut in a direction perpendicular to a long axis is provided with a long width and a short width, and the short axis cross section ratio of the long width WL and the short width Ws is almost uniformly larger than 1 in a long axis direction and is preferably equal to or more than 1.5. The ratio (σ s/Dx) of saturation magnetization (σs) and the X-ray crystal grain size (Dx) is equal to or more than 0.7. |
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