Rare earth magnet alloy ingot, manufacturing method for the same, r-t-b type magnet alloy ingot, r-tb type magnet, r-t-b type bonded magnet, r-t-b type exchange spring magnet alloy ingot, r-t-b type exchange spring magnet, and r-t-b type exchange spring bonded magnet

Abstract

An R-T-B exchange spring magnet alloy ingot is provided, wherein the R-T-B exchange spring magnet alloy ingot comprises at least one element selected from Nd, Pr, and Dy in a total amount of 1 to 12% by atom and B in an amount of 3 to 30% by atom, with a balance being T (T represents a substance predominantly comprising Fe, with a portion of Fe atoms being optionally substituted by Co, Ni, Cu, Al, Ga, Cr, and Mn). The R-T-B exchange spring magnet alloy ingot is produced through formation of a composite of crystal grains of a hard magnetic phase and crystal grains of a soft magnetic phase. The R-T-B exchange spring magnet alloy ingot contains crystal grains of a hard magnetic phase having a grain size of 1 μm or less and crystal grains of a soft magnetic phase having a grain size of 1 μm or less in a volume of at least 50% on the basis of the entire volume of the alloy.

1 . An R-T-B type exchange spring magnet alloy ingot, wherein the R-T-B type exchange spring magnet alloy ingot is produced by receiving a molten alloy of rare earth metal alloy by means of a rotary body; sprinkling the molten alloy by the effect of rotation of the rotary body, and causing the sprinkled molten alloy to be deposited and solidify on an inner wall surface of a rotating cylindrical mold;
 wherein a film having a thermal conductivity lower than that of material comprising the mold is provided to the inner wall surface of the cylindrical mold;   wherein the R-T-B type exchange spring magnet alloy ingot comprises at least one element selected from Nd, Pr, and Dy in a total amount of 1 to 12% by atom and B in an amount of 3 to 30% by atom, with a balance being T (T represents a substance predominantly comprising Fe, with a portion of Fe atoms being optionally substituted by Co, Ni, Cu, Al, Ga, Cr, and Mn);   the R-T-B type exchange spring magnet alloy ingot is produced through formation of a composite of crystal grains of a hard magnetic phase and crystal grains of a soft magnetic phase; and   the R-T-B type exchange spring magnet alloy ingot contains crystal grains of a hard magnetic phase having a grain size of 1 μm or less and crystal grains of a soft magnetic phase having a grain size of 1 μm or less in a volume of at least 50% on the basis of the entire volume of the alloy.   
     
     
         2 . An R-T-B type exchange spring magnet alloy ingot according to  claim 1 , wherein the R-T-B type exchange spring magnet alloy ingot has a thickness of 1 mm or greater as it is casted. 
     
     
         3 . An R-T-B type exchange spring magnet alloy ingot according to  claim 1 , wherein the R-T-B type exchange spring magnet alloy ingot is heat treated at 400 to 1,000° C. after casting. 
     
     
         4 . An R-T-B type exchange spring magnet, wherein the R-T-B type exchange spring magnet is obtainable by mechanical processing at least one method selected from cutting, grinding, polishing, and blanking the R-T-B type exchange spring magnet alloy ingot according to  claim 1 . 
     
     
         5 . An R-T-B type exchange spring magnet according to  claim 4 , wherein the R-T-B type exchange spring magnet has a cylindrical shape having an outer diameter of at least 100 mm. 
     
     
         6 . An R-T-B type exchange spring magnet alloy powder produced through pulverization of the R-T-B type exchange spring magnet alloy ingot according to  claim 1  to a particle size of 500 μm or less. 
     
     
         7 . An R-T-B type exchange spring bonded magnet produced by use of the R-T-B type exchange spring magnet alloy powder according to  claim 6 .