Spindle-shaped magnetic metal particles containing iron as main component and processes for producing the same

摘要

Spindle-shaped magnetic metal particles suitable for use in a magnetic recording medium, which contain iron as a main component, and have an average major axis diameter (L) of 0.05 to 0.15 mu m; a coercive force of 111.4 to 159.2 kA/m; a Co content of from 5 to less than 15 atm% based on whole Fe; a crystallite size of from 150 to less than 170 ANGSTROM ; a ratio of Al to Co from 0.3:1 to less than 2.0:1; a specific surface area (S) represented by the formula: S≤-160 x L + 65; an oxidation stability ( DELTA sigma s) of saturation magnetization of not more than 4.5%; and an ignition temperature of not less than 145 DEG C.