Patent ID: 7255752

Claim:
A method for manufacturing an R-T-B system rare earth permanent magnet comprising a sintered body having 0.03% to 0.25% by weight of Zr, wherein said sintered body comprises a main phase consisting of an R 2 T 14 B phase (wherein R represents one or more rare earth elements, providing that the rare earth elements include Y), and T represents one or more transition metal elements essentially containing Fe, or Fe and Co, and a grain boundary phase containing a higher amount of R than said main phase, wherein a product that is rich in Zr exists in said R 2 T 14 B phase, said manufacturing method comprising the steps of: preparing an R-T-B alloy containing as a main component said R 2 T 14 B phase and also containing the whole amount of Zr, and an R-T alloy containing R and T as main components, wherein the amount of R is higher than that of said R-T-B alloy; obtaining a mixture of a powder of said R-T-B alloy and a powder of said R-T alloy; preparing a compacted body with a certain form from said mixture; and sintering said compacted body, wherein, in said sintering step, said product is generated in said R 2 T 14 B phase; and wherein said R-T-B alloy is prepared by the strip casting method under the condition that the peripheral velocity of a chill roll is 1.0 to 1.8 m/s.