The source of free iron in zinc-bonded permanent magnets based on Sm/sub 2/Fe/sub 17/N/sub x/

The principal phase resulting from the reaction of Sm/sub 2/Fe/sub 17/ with zinc is a solution of Sm in Gamma -Fe-Zn. At the maximum Sm content, this cubic phase with alpha =0.8984 nm has an approximate composition of (at.%) 5 Sm, 42 Fe, 53 Zn, and has no permanent magnetic moment between 4.2 and 600 K. The phase equilibria of the low-Sm alloys in Sm-Fe-Zn show that isostructural Sm/sub 2/Fe/sub 17/ and Sm/sub 2/Zn/sub 17/ are not miscible and that, because of the pervasiveness of equilibria with alpha -Fe, it will be difficult to eliminate alpha -Fe completely from Zn bonded magnets.<
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