Metal treatment – Process of modifying or maintaining internal physical... – Magnetic materials
Patent
1994-10-05
1996-12-03
Sheehan, John
Metal treatment
Process of modifying or maintaining internal physical...
Magnetic materials
148122, H01F 103
Patent
active
055803962
ABSTRACT:
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.
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de la Bathie Rene Perrier
Fruchart Daniel
Fruchart Robert
Miraglia Salvatore
Mollard Paul
Centre National de la Recherche Scientifique "CNRS"
Sheehan John
LandOfFree
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