Method for producing a rare earth metal-iron-boron anisotropic sintered magnet from rapidly-quenched rare earth metal-iron-boron alloy ribbon-like flakes

Claim 1

In a method for producing a rare earth-transition metal-boron (R-T-B) anisotropic sintered magnet by preparing an R-T-B alloy powder containing R 2 T 14 B crystal grains, subjecting the powder to a magnetic field, compacting the powder into a compact body of a desired shape, and inserting the compact body at a sintering temperature thereby to produce the sintered magnet, the improvement wherein said R-T-B alloy powder is a rapidly quenched alloy powder produced by: preparing said R-T-B alloy in a molten state; rapidly quenching said molten R-T-B alloy to form ribbons and/or ribbon-like flakes characterized by a main surface, each ribbon and/or flake having a predetermined thickness and containing said crystal grains uniformly dispersed in said ribbon and/or flake, said crystal grains having an average grain size less than said predetermined thickness and oriented in a direction parallel to the main surface of said ribbons or flakes; and crushing and grinding said ribbons and/or flakes into a powder of an average particle size of a value less than said predetermined thickness but larger than said average grain size, each particle of said powder containing said crystal grains extending in said parallel direction, to thereby enable said powder to be magnetically aligned in said magnetic field.