Grain boundary engineering

Abstract

This disclosure is directed to sintered bodies comprising grains and a grain boundary composition, wherein: (a) the grains comprise a composition substantially represented by a formula G 2 M 14 B, where G is Nd, Dy, Pr, Tb, or a combination thereof, and M is Co, Fe, Ni, or a combination thereof, wherein the grains are optionally doped with one or more rare earth elements; and (b) the grain boundary composition is an alloy composition substantially represented by the formula: Nd 8.5-12.5 Dy 35-45 Co 32-41 Cu 3-6.5 Fe 1.5-5 , wherein the subscript values are atom percent relative to the total composition of the the alloy composition. Corresponding populations of particles are also disclosed

1 - 18 . (canceled) 
     
     
         19 . A method of making a homogeneous powder, comprising:
 pulverizing cast alloy flakes that include a plurality of 2:14:1 phase grains to form a first powder;   sintering a first compact comprising the first powder to create a sintered compact;   fragmenting the sintered compact to form a second powder while maintaining at least some of the 2:14:1 phase grains from the sintered compact;   mixing the second powder with a) a rare earth material R and b) an elemental additive A to produce a homogeneous powder while maintaining at least some of the 2:14:1 phase grains from the second powder;   wherein the rare earth material R includes at least one, at least two, or all three of: i) Nd, ii) Pr, or iii) Dy, and the elemental additive A includes at least one, at least two, or all three of: i) Co, ii) Cu, or iii) Fe.   
     
     
         20 . The method of  claim 19 , further comprising:
 melting magnetic elements to create a molten alloy; and   forming, from the molten alloy, the cast alloy flakes that include the plurality of 2:14:1 phase grains.   
     
     
         21 . The method of  claim 19 , further comprising:
 pressing and aligning particles in the first powder to create the first compact.   
     
     
         22 . The method of  claim 19 , further comprising:
 sintering and magnetizing the homogeneous powder.   
     
     
         23 . The method of  claim 19 , wherein the 2:14:1 phase grains comprise Nd—Fe—B 2:14:1 phase grains. 
     
     
         24 . The method of  claim 19 , wherein the melting comprises induction melting or arc melting. 
     
     
         25 . The method of  claim 19 , wherein the melting comprises melting in an inert atmosphere. 
     
     
         26 . The method of  claim 25 , wherein the inert atmosphere comprises a reducing agent. 
     
     
         27 . The method of  claim 19 , wherein the fragmenting comprises fragmenting with a spray atomizing apparatus. 
     
     
         28 . The method of  claim 19 , wherein the fragmenting comprises fragmenting the sintered compact to an average particle size between 1 to 4 microns. 
     
     
         29 . The method of  claim 19 , wherein the mixing comprises milling, cutting, high energy ball milling, roller milling, sawing, jet milling, tumbling, shaking, jaw crushing, or hydrogen mixing. 
     
     
         30 . The method of  claim 19 , wherein the mixing comprises crushing, grinding, milling, or hydrogen mixing. 
     
     
         31 . The method of  claim 19 , wherein the cast alloy flakes comprise Cu, Co, and Fe and one or more of Nd, Pr, Dy, or Tb. 
     
     
         32 . The method of  claim 19 , wherein the rare earth material R and the elemental additive A form a compound comprising Nd 1-20 Dy 1-60 Co 1-60 Cu 0.1-20 Fe 0.5-90  at. %. 
     
     
         33 . The method of  claim 19 , wherein the rare earth material R and the elemental additive A form a compound comprising Nd 7-14 Dy 30-50 Co 28-45 Cu 1-10 Fe 1-10  at. %. 
     
     
         34 . The method of  claim 19 , wherein the rare earth material R and the elemental additive A form a compound comprising Nd 8.5-12.5 Dy 35-45 Co 32-41 Cu 3-6.5 Fe 1.5-5  at. %. 
     
     
         35 . The method of  claim 19 , wherein the rare earth material R and the elemental additive A form a compound comprising Nd 11.92 Dy 42.32 Co 38.39 Cu 5.34 Fe 2.03  at. % 
     
     
         36 . The method of  claim 34 , wherein the compound comprises between 0.00009 to 0.18 at. % oxygen; or between 0.028 to 0.1 at. % oxygen. 
     
     
         37 . The method of  claim 35 , wherein the compound comprises between 0.00009 to 0.18 at. % oxygen; or between 0.028 to 0.1 at. % oxygen.