Method for forming Fe-B-R-T alloy powder by hydrogen decrepitation of die-upset billets

Claim 1

A method for treating an Fe-B-R-T permanent magnet alloy, in which R is at least one of yttrium, scandium, lanthanum, the rare earth elements in the lanthanoid series, or mixture thereof, and in which T is at least one transition element at least one element selected from the group consisting of gallium, silicon, aluminum, zinc, or mixtures thereof, said method comprising the sequential steps of: subjecting the Fe-B-R-T alloy to a die upsetting operation to form a die-upset alloy; heating said die-upset Fe-B-R-T alloy in a hydrogen-containing atmosphere at a pressure between 250 and 760 mm Hg at a first temperature and for a time sufficient to bring about substantially hydriding of said alloy, said first temperature being up to about 500° C; and heating said hydrided Fe-B-R-T ally by linearly increasing the temperature of said alloy from said first temperature to a second temperature of about 400° to 650° C. in a vacuum of no more than 10 -2 mm Hg or in an inert atmosphere having a partial pressure of hydrogen of no more than 10 -2 mm Hg, for a time sufficient to bring about substantially complete dehydriding of said alloy; said time, said first temperature and said second temperature and pressure of hydriding and dehydriding being selected together so as to yield a resulting alloy powder or readily friable Fe-B-R-T alloy material having good intrinsic magnet coercivity, while avoiding the growth of large crystals in said resulting alloy.

Claim 2

A method for treating an Fe-B-R-T permanent magnet alloy, in which R is at least one of yttrium, scandium, lanthanum, the rare earth elements in the lanthanoid series, or mixture thereof, and in which T is at least one transition element at least one element selected from the group consisting of gallium, silicon, aluminum, zinc, or mixtures thereof, said method comprising the sequential steps of: subjecting the Fe-B-R-T alloy to a die upsetting operation to form a die-upset alloy; heating said die-upset Fe-B-R-T alloy in a hydrogen-containing atmosphere at a pressure between 250 and 760 mm Hg at a first temperature and for a time sufficient to bring about substantially hydriding of said alloy, said first temperature being up to about 500° C; and heating said hydrided Fe-B-R-T ally by linearly increasing the temperature of said alloy from said first temperature to a second temperature of about 400° to 650° C. in a vacuum of no more than 10 -2 mm Hg or in an inert atmosphere having a partial pressure of hydrogen of no more than 10 -2 mm Hg, for a time sufficient to bring about substantially complete dehydriding of said alloy; said time, said first temperature and said second temperature and pressure of hydriding and dehydriding being selected together so as to yield a resulting alloy powder or readily friable Fe-B-R-T alloy material having good intrinsic magnet coercivity, while avoiding the growth of large crystals in said resulting alloy.