A very small amount of a rare earth metal-containing iron and its manufacturing method, a permanent

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PROBLEM TO BE SOLVED : To attain a high saturation magnetic flux density by an arrangement wherein x and y in the compositional formula have specified atomic compositions, iron, an alloy of iron and boron and a compound having a specified R-Fe-B type crystal structure are included as compositional phases, and the mean crystal grain size of each compositional phase is specified. SOLUTION : The iron based permanent magnet is shown by a compositional formula Fe100-x-yBxRy (Fe is iron, B is boron, R is at least one kind of rare earth element selected from a group of Y, La, Ce, Pr, Nd and Sm) wherein x and y satisfy the following relationship; 15 at.%<=x<=30 at.% and 0.1 at.%<=y<=3 at.%. A soft magnetic alloy composition phase of iron and an alloy of iron and boron is mixed with a soft magnetic compound phase having R2Fe14B type crystal structure and mean crystal grain size of each composition is 100 nm or less. The rectangularity ratio is 0.8 or above, remanent magnetic flux density is 1.3 T or above and intrinsic coercive force is 20 kA/m or above.