R-T-B BASED RARE EARTH PERMANENT MAGNET

文件类型：PDF文档
文件大小：463K
An R-T-B based rare earth permanent magnet is expressed by a compositional formula : (R11-x(Y1-y-z Cey Laz)x)aTbBcMd in which R1 is one or more kinds of rare earth element not including Y, Ce and La, “T” is one or more kinds of transition metal, and includes Fe or Fe and Co as an essential component, “M” is an element having Ga or Ga and one or more kinds selected from Sn, Bi and Si, and 0.4≦x≦0.7, 0.00≦y+z≦0.20, 0.16≦a/b≦0.28, 0.050≦c/b≦0.075 and 0.005≦d/b≦0.028. The magnet includes a main phase, including a compound having a R2T14B type tetragonal structure, and a grain boundary phase. D10, D50, D90 of crystal grain diameter according to the main phase crystal grains satisfies the following formula : D50≦4.00 μm and (D90−D10)/D50≦1.60. A coating rate of the grain boundary is 70.0% or more.