非晶晶化过程中Nd_2Fe_(14)B相和α-Fe相的析出与长大及其磁性能

Precipitation and growth of Nd_2Fe_(14)B/α-Fe during amorphous crystallized process and its magnetic properties

利用X射线衍射(X-ray diffraction,XRD)分析仪、振动样品磁强计(vibrating sample magnetometer,VSM)和差示扫描量热仪(differential scanning calorimeter,DSC),研究了非晶Nd9.5Fe76Co5Ti3B6.5合金条带晶化过程中Nd_2Fe_(14)B/α-Fe析出相的相结构及其磁性能的变化.结果表明,在晶化过程中Nd_2Fe_(14)B相和α-Fe相分别在600,680?C退火时析出.随着退火温度的升高,α-Fe相的晶粒比Nd_2Fe_(14)B相长大更明显:当温度由690?C升高到700?C时,α-Fe相及Nd_2Fe_(14)B相的晶粒尺寸分别由22.4,32.8 nm长大到33.3,39.8 nm.在690?C退火时,硬磁相Nd_2Fe_(14)B和软磁相α-Fe之间具有较强的交换耦合作用,其晶粒尺寸分别为32.8,22.4 nm.此时的合金具有最佳的综合磁性能:剩磁强度Br=0.88 T,矫顽力Hci=523.76 k A/m,最大磁能积(BH)max=100.01 k J/m^3.

The crystal structure, magnetic properties of the Nd9.5Fe76Co5Ti3B6.5 amorphous alloys annealed at different temperatures were investigated by X-ray diffraction （XRD）, vibrating sample magnetometer （VSM）, and differential scanning calorimeter （DSC） The results indicated that the Nd2Fe14B phase was precipitated prior to that of α-Fe phase from the amorphous matrix. Nd2Fe14B phase and α-Fe phase were precipitated at 600 and 680 ℃, respectively, α-Fe phase grain growed up more obviously than Nd2Fe14B phase with increasing annealing temperature. The grain sizes of α-Fe phase and Nd2Fe14B phase growed from 22.4 and 32.8 nm to 33.3 and 39.8 nm when they annealed at 690 to 700 ℃.When annealing at 690℃, there were strong exchange coupling effects between hard mag- netic phase Nd2Fe14B with 32.8 nm and soft magnetic phase α-Fe with 22.4 nm. Mean-while Nd9.5Fe76Co5Ti3B6.5 alloy obtained the best magnetic properties with Br =0.88 T, Hci =523.76 kA/m, and （BH）max=100.01 kJ/m^3.