A method of the type described above is disclosed, for instance, in the publication Journal of Applied Physics, Vol. 57, No. 1, Apr. 15, 1985, pages 4149 to 4151. For some time, new permanent magnet materials of metal/metal/metalloid systems have been known which exceed by far all materials known to date with respect to the most important hard-magnetic variable, namely, the energy product. Preferred materials of these systems have substantially the composition Nd.sub.2 Fe.sub.14 B, wherein a partial substitution of the mentioned elements or slight deviations from the stoichiometry of this tetragonal phase are possible in order to thus optimize the microstructure of the materials. For the manufacturer of such permanent magnet materials on a large technical scale, in particular, two methods are used. According to the method of European Patent EP 0 126 802 A1, an alloy of the desired composition is first melted, subsequently comminuted to form a fine pulver, magnetically oriented in a magnetic field, and then compacted by a pressure and sintering treatment. In the method disclosed in European Patent EP 0 144 112 A 1, an intermediate product is first produced by fast quenching from the melt of the starting components, which is then compacted by hot pressing, and thereafter oriented in a further process step, the so-called "die-upsetting", in the preferred magnetic direction. See, for example, Applied Physics Letters, Vol. 46, No. 8, Apr. 15, 1985, pages 790 and 791. Materials which have been produced according to these two methods differ primarily with respect to their microstructure. While in the method of EP 0 126 802 A1, a relatively coarse grain structure with several foreign phases develops, the samples which were quenched fast according to the EP 0 144 112 A1 method are characterized by an extremely fine grain structure which in this case causes the anchoring of the Bloch walls, responsible for a magnetization reversal.
Besides these two methods, it is known from the Journal of Applied Physics, Vol. 57, No. 1, pages 4149 to 4151 (1985) that for the manufacture of permanent magnet material to use as the starting components Fe--, Fe.sub.2 B-- and Nd-- powder which are subsequently compacted and sintered. In the process, the desired phase is formed by diffusion. In order to obtain a magnetically anisotropic material, however, this sintered material must subsequently be comminuted again and, after magnetic orientation, compacted and sintered again. Thus, this prior art method for the manufacture of permanent-magnet materials with magnetic anisotrophy is relatively expensive.
USPTO Backgrounds
USPTO Backgrounds