Nd-Fe-B Permanent Magnetic Material

Abstract

Permanent magnetic materials comprising an Nd—Fe—B alloy and an additive comprising at least one boride are disclosed. The boride may be a lanthanide boride being about 0.01% to about 5% of the alloy by weight. In some instances, the lanthanide boride may be at least one of DyB 6 , GdB 6 , TbB 6 , SmB 6 , or mixtures thereof.

1 . A permanent magnetic material comprising:
 an Nd—Fe—B alloy; and   an additive comprising at least one boride.   
   
   
       2 . The material of  claim 1 , wherein the amount of boride is from about 0.01% to about 5% of the alloy by weight. 
   
   
       3 . The material of  claim 1 , wherein the boride is a lanthanide boride. 
   
   
       4 . The material of  claim 3 , wherein the lanthanide boride includes at least one member selected from the group consisting of DyB 6 , GdB 6 , TbB 6  and SmB 6 . 
   
   
       5 . The material of  claim 3 , wherein the lanthanide boride includes TbB 6  and a first compound selected from the group consisting of DyB 6 , GdB 6  and SmB 6 , and wherein the weight ratio of the TbB 6  to the first compound is from about 1:1 to about 50:1. 
   
   
       6 . The material of  claim 1 , wherein the alloy has the following general formula:
   Nd a R b Fe 100-a-b-c-d M c B d , wherein:   R is at least one element selected from the group consisting of Pr, Dy and Tb;   M is at least one element selected from the group consisting of Nb, Co, Ga, Zr, Al, Cu and Ti; and   10≦a≦20, 0≦b≦8, 0≦c≦6 and 5≦d≦7.   
   
   
       7 . A permanent magnetic material comprising:
 an Nd—Fe—B alloy, wherein the alloy has the following general formula:
   Nd a R b Fe 100-a-b-c-d M c B d , wherein: 
   R is at least one element selected from the group consisting of Pr, Dy and Tb;   M is at least one element selected from the group consisting of Nb, Co, Ga, Zr, Al, Cu and Ti; and   10≦a≦20, 0≦b≦8, 0≦c≦6 and 5≦d≦7; and   an additive comprising at least one lanthanide boride.   
   
   
       8 . The material of  claim 7 , wherein the amount of lanthanide boride is from about 0.01% to about 5% of the alloy by weight. 
   
   
       9 . The material of  claim 7 , wherein the lanthanide boride includes at least one member selected from the group consisting of DyB 6 , GdB 6 , TbB 6  and SmB 6 . 
   
   
       10 . The material of  claim 7 , wherein the lanthanide boride includes TbB 6  and a first compound selected from the group consisting of DyB 6 , GdB 6  and SmB 6 , and wherein the weight ratio of the TbB 6  to the first compound is from about 1:1 to about 50:1. 
   
   
       11 . A method of preparing a permanent magnetic material, the method comprising:
 mixing an Nd—Fe—B alloy and an additive to form a mixture;   pressing the mixture in a magnetic field to form a composition;   sintering the composition to a first temperature; and   tempering the composition to a second temperature, wherein the sintering and tempering steps can occur under a first atmosphere.   
   
   
       12 . The method of  claim 11 , wherein the first atmosphere is at least one of vacuum or inert gas. 
   
   
       13 . The method of  claim 11 , wherein the additive comprises at least one boride, and wherein the amount of boride is from about 0.01% to about 5% of the alloy by weight. 
   
   
       14 . The method of  claim 13 , wherein the boride includes at least one member selected from the group consisting of DyB 6 , GdB 6 , TbB 6  and SmB 6 . 
   
   
       15 . The material of  claim 13 , wherein the boride includes TbB 6  and a first compound selected from the group consisting of DyB 6 , GdB 6  and SmB 6 , and wherein the weight ratio of the TbB 6  to the first compound is from about 1:1 to about 50:1. 
   
   
       16 . The method of  claim 11 , further comprising mixing the alloy and the additive with an antioxidant and a lubricant, wherein the amount of antioxidant is from about 0.01% to about 5% of the alloy by weight, and wherein the amount of lubricant is from about 0% to about 5% of the alloy by weight. 
   
   
       17 . The method of  claim 11 , wherein the alloy has the following general formula:
   Nd a R b Fe 100-a-b-c-d M c B d , wherein:   R is at least one element selected from the group consisting of Pr, Dy and Tb;   M is at least one element selected from the group consisting of Nb, Co, Ga, Zr, Al, Cu and Ti; and   10≦a≦20, 0≦b≦8, 0≦c≦6 and 5≦d≦7.   
   
   
       18 . The method of  claim 11 , wherein the average particle diameter of the alloy is from about 2 to about 10 microns, and wherein the average particle diameter of the additive is from about 2 to about 1000 nanometers. 
   
   
       19 . The method of  claim 11 , wherein the pressing step has an intensity of from about 1.2 to about 2.0 T, a pressure of from about 10 to about 200 MPa, and a period of from about 10 to about 60 seconds. 
   
   
       20 . The method of  claim 11 , wherein the first temperature is from about 1030 to about 1120° C. for a period of from about 2 to about 4 hours, and wherein the second temperature is from about 500 to about 920° C. for a period of from about 2 to about 8 hours.