R-Fe-B sintered magnet

• Main Authors: Ohashi, Tetsuya, Kume, Tetsuya, Hirota, Koichi, Nakamura, Hajime
• Format: Patent
• Language: English
• Published: 09.08.2022
• Subjects: ALLOYS; BASIC ELECTRIC ELEMENTS; CASTING; CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; ELECTRICITY; FERROUS OR NON-FERROUS ALLOYS; INDUCTANCES; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MAGNETS; MAKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; METALLURGY; PERFORMING OPERATIONS; POWDER METALLURGY; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TRANSFORMERS; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS; WORKING METALLIC POWDER

An R-Fe-B base sintered magnet is provided comprising a main phase containing an HR rich phase of (R′,HR)2(Fe,(Co))14B 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)-M1 phase in the form of an amorphous phase and/or nanocrystalline phase, the (R′,HR)-Fe(Co)-M1 phase consisting essentially of 25-35 at % of (R′,HR), 2-8 at % of M1 which 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.