Patent ID: 7357880

Claim:
A composite rare-earth anisotropic bonded magnet, comprising: (A) Cobalt-less R1 d-HDDR coarse powder with an average grain diameter of 40-200 μm and having micro-cracks, comprising: 1. Cobalt-less R1 d-HDDR anisotropic magnet powder, obtained by performing a d-HDDR treatment on a cobalt-less R1 alloy of a rare-earth element including yttrium (Y) (hereafter, “R1”), iron (Fe), and boron (B) as the main ingredients and fundamentally not containing cobalt; and 2. #1 surfactant that coats at least one part of the grain surface of said cobalt-less R1 d-HDDR anisotropic magnet powder; and (B) R2 fine magnet powder with an average aspect ratio of 2 or less and average grain diameter 1-10 μm, comprising: 1. R2 anisotropic magnet powder with a maximum energy product (BH)max 240 kJ/m 3 or more and with a rare-earth element including yttrium (hereafter, “R2”) as one of the principle ingredients; and 2. #2 surfactant that coats at least one part of the grain surface of said R2 anisotropic magnet Powder and (C) a thermosetting resin as binder; wherein the said bonded magnet contains 50-84 wt % of said Co-less R1 d-HDDR coarse magnet powder, 15-40 wt % of said R2 fine magnet powder, and 1-10 wt % of said thermosetting resin; and wherein relative density (ρ/ρ th ) of the said bonded magnet, which is the ratio of volume density (ρ) to theoretical density (ρ th ), is 91-99%; and wherein normalized grain count of the said Co-less R1 d-HDDR coarse magnet powder in the said bonded magnet, where per unit area apparent grain diameter is 20 μm or less, is 1.2×10 9 pieces/m 2 or less; the said composite rare-earth anisotropic bonded magnet having the special characteristics of outstanding magnetic properties and heat tolerance.