29-03-2018 дата публикации
Номер: US20180090250A1
An R—Fe—B base sintered magnet is provided comprising a main phase containing an HR rich phase of (R′, HR)(Fe,(Co))B wherein R′ is an element selected from yttrium and rare earth elements exclusive of Dy, Tb and Ho, and essentially contains Nd, and HR is an element selected from Dy, Tb and Ho, and a grain boundary phase containing a (R′, HR)—Fe(Co)-Mphase in the form of an amorphous phase and/or nanocrystalline phase, the (R′, HR)—Fe(Co)-Mphase consisting essentially of 25-35 at % of (R′, HR), 2-8 at % of Mwhich is at least one element selected from Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, up to 8 at % of Co, and the balance of Fe. The HR rich phase has a higher HR content than the HR content of the main phase at its center. The magnet produces a high coercivity despite a low content of Dy, Tb and Ho. 1. An R—Fe—B base sintered magnet of a composition consisting essentially of 12 to 17 at % of R which is at least one element selected from yttrium and rare earth elements and essentially contains Nd , 0.1 to 3 at % of Mwhich is at least one element selected from the group consisting of Si , Al , Mn , Ni , Cu , Zn , Ga , Ge , Pd , Ag , Cd , In , Sn , Sb , Pt , Au , Hg , Pb , and Bi , 0.05 to 0.5 at % of Mwhich is at least one element selected from the group consisting of Ti , V , Cr , Zr , Nb , Mo , Hf , Ta , and W , 4.8+2×m to 5.9+2×m at % of boron wherein m is at % of M , up to 10 at % of Co , up to 0.5 at % of carbon , up to 1.5 at % of oxygen , up to 0.5 at % of nitrogen , and the balance of Fe , and containing an intermetallic compound R(Fe ,(Co))B as a main phase , wherein{'sub': 1', '1', '1, 'the magnet contains the main phase and a grain boundary phase between grains of the main phase, the grain boundary phase containing a (R′, HR)—Fe(Co)-Mphase in the form of an amorphous phase and/or nanocrystalline phase having a grain size of up to 10 nm, the (R′, HR)—Fe(Co)-Mphase consisting essentially of 25 to 35 at % of (R′, HR), 2 ...
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