| 简介 |
SOLUTION : An R-Fe-B based sintered magnet has main phases of an R2(Fe, (Co))14B intermetallic compound, and includes boride phases of Ti or the like and no R1.1Fe4B4 compound phase at triple points of grain boundaries. The R-Fe-B based sintered magnet has a core-shell structure in which the main phases are coated by : R(R represents a rare earth element, including Nd and Pr as essential elements)-Fe(Co)-M1(including Si and Al) phases of amorphous and/or micro crystalline; or grain boundary phases including the R-Fe(Co)-M1 phases, and crystal phase or micro crystalline and amorphous R-M1 phases with R accounting for 50 atom% or more. The superficial area coverage of the R-Fe(Co)-M1 phases concerning the main phases is 50% or more. The phase width of the grain boundary phase located between two grains of the main phases is 10 nm or larger, which is 50 nm or larger on average. The average crystal grain diameter after the sintering is 6 μm or less. The crystal orientation degree is 98% or more. The magnetization rate is 96% or more.
EFFECT : An R-Fe-B based sintered magnet of the present invention offers a coercive force of 10 kOe or more and a magnetization rate of 96% or more regardless of whether a small amount of Dy, Tb and Ho or none of them is included.
SELECTED DRAWING : Figure 1
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