Metal treatment – Process of modifying or maintaining internal physical... – Magnetic materials
Patent
1990-04-20
1992-09-01
Sheehan, John P.
Metal treatment
Process of modifying or maintaining internal physical...
Magnetic materials
148103, 148104, 148105, 419 12, 419 33, 419 38, 241 18, 241 24, 241 29, H01F 102
Patent
active
051435608
ABSTRACT:
A method for the high volume manufacture of Fe-B-R-T alloy powders without sacrificing the resultant magnetic properties (such as intrinsic magnetic coercivity) of the alloy involves hydrogen decrepitation of vacuum cast or die-upset billets of the alloy. Hydriding is carried out at a partial pressure of hydrogen of between 250 and 760 mm Hg at 100.degree. to 500.degree. C. for 30 minutes to 6 hours or longer, depending upon load size. Dehydriding occurs in a vacuum below 10.sup.-2 mm Hg or in an inert atmosphere possessing a partial pressure of hydrogen below 10.sup.-2 mm Hg. The alloy powder is preferably incorporated in matrix or composite magnets by the addition of a binder prior to pressing and orienting. The binder may set during pressing in a hot die, or by heating after pressing in a cold die.
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Hitachi Metals, Inc., Ltd.
Sheehan John P.
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