Magnetic properties and microstructure of (Nd,Dy)-(Fe,Co)-B system magnets

The magnetic properties of sintered (Nd,Dy)-(Fe,Co)-B system magnets were studied and compared with their microstructures. Both cobalt and dysprosium substitutions for Nd-Fe-B ternary alloy are effective for the increase of the Curie temperature. It is confirmed that the replacement of iron by cobalt in this system improves the temperature coefficient of coercivity. The microstructure studies show that the simultaneous substitution of cobalt and dysprosium produces cobalt-rich compounds in the grain boundary region. These c0balt-rich phases are supposed to contribute to the lower coercivity of this system