Method of fabrication of mixed rare-earth permanent magnet

Abstract

A method of producing a permanent magnet includes: melting boron, cobalt, a metallic alloy component, a mixed rare earth material, and iron together to form a melted alloy and forming a first alloy ingot using the melted alloy, wherein the permanent magnet comprises about 28-35 weight percent of rare earth material; crushing the first alloy ingot into particles having a first average particle diameter less than about 3 millimeters; milling the particles to form a powder mixture with a second average particle diameter in the range from about 2.5-5 microns; shaping the powder mixture, in a magnetic field, into a powder compact; sintering the powder compact at a temperature ranging from about 1020-1120 degrees centigrade for a time duration ranging from about 1-5 hours to form a second ingot; and aging the second ingot at a temperature ranging from about 450-650 degrees centigrade for time duration ranging from about 1-5 hours

1 . A method of producing a permanent magnet comprising:
 melting boron, cobalt, a metallic alloy component (M), a mixed rare earth material, and iron together to form a melted alloy and forming a first alloy ingot using the melted alloy, wherein the permanent magnet comprises about 28-35 weight percent of rare earth material;   crushing the first alloy ingot into particles having a first average particle diameter less than about 3 millimeters;   milling the particles to form a powder mixture with a second average particle diameter in the range from about 2.5-5 microns;   shaping the powder mixture, in a magnetic field, into a powder compact;   sintering the powder compact at a temperature ranging from about 1020-1120 degrees centigrade for a time duration ranging from about 1-5 hours to form a second ingot; and   aging the second ingot at a temperature ranging from about 450-650 degrees centigrade for time duration ranging from about 1-5 hours.   
     
     
         2 . The method of  claim 1  further comprising pressing the powder compact isostatically in oil under a pressure of about 100-300 MPa. 
     
     
         3 . The method of  claim 1 , wherein the metallic alloy component is selected from a group consisting of aluminum, copper, niobium, gallium, vanadium, chromium, zirconium, or any combination thereof. 
     
     
         4 . The method of  claim 1 , wherein the mixed rare earth material comprises light rare-earth material and heavy rare-earth material, and wherein the light rare-earth material comprises at least about 50 weight percent of praseodymium and about 5-50 weight percent of neodymium. 
     
     
         5 . The method  claim 4 , wherein the mixed rare-earth material comprises about 3-45 weight percent of heavy rare-earth material, and wherein the heavy rear-earth material comprises dysprosium or a combination of dysprosium and terbium. 
     
     
         6 . The method of  claim 5 , wherein the heavy rare-earth material comprises a combination of dysprosium and terbium, and wherein the permanent magnet comprises about 3 weight percent of terbium. 
     
     
         7 . The method of  claim 1 , wherein crushing comprises decrepitating the first alloy ingot under a room temperature with a hydrogen pressure ranging from about 0.1-0.8 Mpa for a time duration of at least 1 hour, and then de-hydrogenating in a vacuum environment at a temperature ranging from about 500-700 degrees centigrade with a pressure ranging from about 0-1000 Pa for a time duration of about 1-12 hours. 
     
     
         8 . The method of  claim 1 , wherein shaping comprises pressing the powder mixture into a powder compact in a magnetic field of about 1.2-3.0 Tesla. 
     
     
         9 . The method of  claim 8  further comprising isostatically pressing the powder compact in oil under a pressure of about 100-300 MPa. 
     
     
         10 . The method of  claim 1 , wherein an average grain size of the permanent magnet ranges from about 5-18 microns.