A new type of soft ferromagnetic alloys: RFe12−xGex

Abstract Ternary iron-rich rare earth germanides RFe 12− x Ge x with R=Y, La, Ce, Nd, Sm, Gd, Dy, Ho and Er reveal soft ferromagnetic properties. The structure, the microstructure and the soft magnetic properties of these materials have been studied versus the germanium content and the nature of the rare earth element. In the as-cast materials, at least three crystallized phases have been identified: α-Fe(Ge), RFe 2 Ge 2 and traces of Fe 3 Ge. The typical grain size is of some tens of micrometer. The Curie temperature of these alloys is rather high (i.e. >770 K). The transition temperature as well as the saturation magnetization are found to strongly depend on the nature of the R element. The rapidly quenched alloys appear fully homogenized compared with the as-cast materials and the grain size decreases to about one micrometer. Although X-ray diffraction patterns have shown that the two major phases remain present, the magnetic characteristics are fairly dependent on the earth rare element. For all the investigated materials, measurements of the hysterical behaviour reveal a very low coercivity level, i.e. H c