Magnetic Properties of (Fe-Co)<I><SUB>m</SUB></I>(Pr, Sm)<I><SUB>n</SUB></I> (<I>m</I>⁄<I>n</I>=17⁄2, 5/1, 7/2) Compounds Prepared by Rapid Quenching Technique

Coercivity, magnetization, Curie temperature and maximum energy product of rapidly quenched (Fe1−xCox)1−y(Sm, Pr)y (0≤x≤1.0; y=0.11, 0.17 and 0.22) alloys were measured. The coercivity at room temperature is: 480-1120 kA/m for (Fe1−xCox)0.83Sm0.17 (CaCu5 type, 0.6≤x≤1.0), 240-480 kA/m for (Fe1−xCox)0.83Pr0.17 (CaCu5 type, 0.6≤x≤1.0), 240-500 kA/m for (Fe1−xCox)0.78Pr0.22 (Gd2Co7 type, 0.6≤x≤1.0), 64-160 kA/m for (Fe1−xCox)0.89Pr0.11 (TbCu7 type, 0≤x≤0.6), and 4-64 kA/m for (Fe1−xCox)0.89Pr0.11 (TbCu7 type, 0≤x≤1.0).The magnetic anisotropy and coercivity of the alloys are discussed on the basis of the single ion model. The composition dependence of coercivity in the (Fe-Co)0.83Sm0.17 and (Fe-Co)0.89Sm0.11 alloys are attributed to the change of both lattice constant and molecular field.