Centre National De La Recherche Scientifique

Robert Fruchart

Daniel Fruchart

Roland Madar

Salvatore Miraglia

Rene Perrier De La Bathie

Paul Mollard

Alain Rouault

Daniel Boursier

Pierre Taunier

Philippe L'Heritier

Patrick Chaudouet

There is disclosed a process for optimizing the magnetic properties of a multiphase product of composition rare earth/iron/boron endowed with permanent magnet properties at ambient temperature. This composition serves as a precursor, which is first subjected to a decrepitation treatment by hydrogenation under low pressure at low temperature to obtain an intermediate hydride in pulverulent form. The pulverulent intermediate hydride is subsequently subjected to a first heat treatment under vacuum for partial dehydrogenation at a temperature below its element separation temperature. The non-separated product thereby obtained is subjected to a second heat post-treatment under an initial primary vacuum and extensively dehydrogenated until the primary vacuum is reestablished at a temperature close to 600.degree. C. The precursor can be an isotropic material obtained by fast quenching, such as wheel quenching or hot welding with a forging ratio of at least 10. According to another aspect of the invention the dehydrogenated product obtained is subjected to a third heat post-treatment under a neutral atmosphere or under vacuum, at a temperature of between 450.degree. and 1000.degree. C. The two post-treatments are optionally separated by a thermal plateau.

Treatment of pulverant magnetic materials and products thus obtained

New magnetic hydride Nd.sub.2 Fe.sub.14 BH.sub.x (0&lt;x&lt;5) and family corresponding to other rare earths and yttrium. Possible substitution of Fe by Co. Preparation from Nd.sub.2 Fe.sub.14 B by hydrogenation (ambient temperature; pH.sub.2 &gt;20 bar), which can be reversed to give powdered Nd.sub.2 Fe.sub.14 B. Remarkable magnetic properties.

Magnetic rare earth/iron/boron and rare earth/cobalt/boron hydrides, the

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La Tronche, France

Robert Fruchart