RE-Fe-B magnets and manufacturing method for the same

DETAILED DESCRIPTION In accordance with the invention, a permanent magnet alloy is provided consisting essentially of, in weight percent, 27 to 35, preferably 29 to 34 of a rare earth element, including Nd in an amount of at least 50% of the total amount of the rare earth element content, 0.
8 to 1.
3, preferably 0.
9 to 1.
2 B, up to 30, preferably 15 Co, 40 to 75 Fe, 0.
03 to 0.
3, preferably 0.
05 to 0.
15 C, 0.
2 to 0.
8, preferably 0.
3 to 0.
8 oxygen, up to 1, and preferably 0.
5 of at least one of Cu, Ga and Ag.
The alloy can further include up to 5 of at least one additional transition element selected from the group consisting of Al, Si, Sn, Zn, Nb, Mo, V, W, Cr, Zr, Hf, Ti, and Mg.
Cu, Ga and Ag may be present within the range of 0.
02 to 0.
5%, preferably 0.
05 to 0.
5%.
At least one of Pr or La may be substituted for up to 50% of the Nd.
Likewise, at least one of Dy or Tb may be substituted for up to 50% of the Nd.
Co may be present within the range of 0.
5 to 5%.
Cu may be present within the range of 0.
02 to 0.
5%.
In accordance with the method of the invention, the above permanent magnet alloy is produced from prealloyed particles and/or blends of prealloyed particles.
This may be achieved by the conventional practice of comminuting a casting of the alloy or atomization of the molten alloy as by the use of an inert atomizing gas in accordance with this well known practice.
The prealloyed particles or blends thereof are contacted with a carbon containing material to produce a carbon content therein of 0.
03 to 0.
3% and preferably 0.
05 to 0.
15%.
The carbon containing material may be a metal stearate, preferably zinc stearate.
After contact with the zinc stearate, the size of the particles may be reduced by well known practices, such as jet milling.
The particles are also contacted with an oxygen containing material to produce an oxygen content therein of 0.
2 to 0.
8% and preferably 0.
3 to 0.
8%.
The oxygen containing material may be air.
The particles may be contacted with air either during or after the size reduction thereof, including during a milling operation for reducing the size of the particles