Title :
Grain growth kinetics in sintered Nd-Fe-B magnets
Author :
Rodewald, W. ; Wall, B. ; Fernengel, W.
Author_Institution :
Vacuumschmelze GmbH, Hanau, Germany
fDate :
9/1/1997 12:00:00 AM
Abstract :
The topology of the microstructure and the grain growth kinetics of Nd-Fe-B magnets have been examined after sintering-time intervals between 0.5 and 19 h by metallographic analysis. In dense magnets about 80% of the grains have 5 to 7 corners. The fraction of grains with >8 corners increases with sintering-time and the amount of liquid phase during sintering. The grain growth exponents amount to n≈25 to 30 for small grains (≪10 μm) and to n≈1 to 4 for large grains (≫10 μm) revealing the intensive growth of large grains. Dense Nd-Fe-B magnets with an average grain size between 6.2 and 7.4 μm reach a maximum energy density of 53 MGOe
Keywords :
coercive force; crystal microstructure; demagnetisation; ferromagnetic materials; grain growth; grain size; iron alloys; metallography; neodymium alloys; permanent magnets; powder metallurgy; remanence; sintering; 0.5 to 19 h; 10 mum; 6.2 to 7.4 mum; Nd-Fe-B; coercivity; corners; demagnetization; dense Nd-Fe-B magnets; dense magnets; grain growth exponents; grain growth kinetics; grain size; large grains; liquid phase; maximum energy density; metallographic analysis; microstructure; remanence; sintered Nd-Fe-B magnets; sintering-time intervals; small grains; topology; Anisotropic magnetoresistance; Grain boundaries; Grain size; Kinetic theory; Magnetic analysis; Magnets; Microstructure; Powders; Temperature; Topology;
Journal_Title :
Magnetics, IEEE Transactions on
