Aimants Ugimag Sa

Aimants Ugimag

Philippe Tenaud

Masato Sagawa

Fernand Vial

Pierre Turillon

Armand Gabriel

The invention relates to a method of obtaining friable and relatively inert TR Fe B type magnetic materials in divided form which lead to magnets having improved corrosion resistance. This method involves treating the material in an atmosphere containing (or capable of containing) hydrogen under the following conditions of absolute pressure (P) and of temperature (T.degree. C.): if P.ltoreq.Pa, 250&lt;T&lt;550; and if P&gt;Pa, 250+100 log (P/Pa)&lt;T&lt;250+100 log (P/Pa) log base 10, Pa being atmospheric pressure. The invention is used for obtaining sintered TR Fe B magnets having improved corrosion resistance.

Method of obtaining a magnetic material of the rare earth/transition

The invention relates to Fe Nd B type alloys for permanent magnets, the permanent magnets thus obtained and a method of producing them. They have high magnetic characteristics with good temperature resistance and good resistance to atmospheric corrosion. They comprise, in at%, 12 to 18% of rare earths, 3 to 30% of Co, 5.9 to 12% of B, 2 to 10% of V, some Al and Cu, the remainder being iron and unavoidable impurities. The V can be substituted by other refractory elements (Nb, W, Cr, Mo, Ti, Zr, Hf, Ta). The method mainly involves sintering at between 1050 and 1110.degree. C. followed by annealing at between 850 and 1050.degree. C. and/or artificial ageing at between 560.degree. C. and 850.degree. C.

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Crolles, France

Philippe Tenaud