晶化对Co_(43)Fe_(20)Ta_(5.5)B_(31.5)非晶合金磁性能的影响

Effect of Crystallization on Magnetic Properties of Co_(43)Fe_(20)Ta_(5.5)B_(31.5) Amorphous Alloy

采用单辊甩带法制备了Co43Fe20Ta5.5B31.5非晶合金薄带,利用差热分析、X-射线衍射以及振动样品磁强计研究了等温晶化和非等温晶化条件下晶化对显微组织和磁性能的影响。结果表明,等温晶化时,饱和磁感应强度Ms和矫顽力Hc都随晶化体积分数α的增加而增加。经过928K保温55min的晶化处理以后,合金的Ms值由制备态的37.2增加到58.4A·m2/kg,与此同时矫顽力也由制备态的1.25×79.6A/m增加到634.45×79.6A/m。当只有(Co,Fe)21Ta2B6相析出时,Hc和Ms的增加幅度都比较小。随着晶化的进行,当晶体相(Co,Fe)3B2和(Co,Fe)B析出时Hc和Ms都发生突然增高。在非等温晶化条件下,Ms随终止温度的提高而单调增大,但增加幅度很小。Hc随终止晶化温度的提高而变化的幅度较大,并且变化非单调。在第1个晶化峰温度范围之内时,Hc随终止温度升高而提高,但终止温度高于第2个晶化峰结束温度时,矫顽力又急剧下降。终止温度从968K提高到1153K时,Ms从61.74增加到67.7A·m2/kg,矫顽力由267.6×79.6增加到416.2×79.6A/m。当终止温度进一步提高到1273K时,矫顽力又下降为152.2×79.6A/m。

The Co43Fe20Ta5.5B31.5 amorphous ribbons were prepared by melt spinning. The effects of the crystallization under isothermal and non-isothermal conditions on microstructure and magnetic properties were investigated using X-ray diffraction （XRD）, differential thermal analyzer （DTA）, and vibrating samples magnetometer （VSM）. It is found that the saturation magnetization Ms and the coercivity Hc increase with increasing of the crystallized volume fraction a under the condition of isothermal annealing. The Hc value of the alloy changes from 1.25×79.6 A/m for as-cast sample to 634.45 × 79.6 A/m for sample annealed at 928 K for 55 min, and at the same time the M, value changes from 37.2 to 58.4 （A·m^2）·kg^-1. In the initial crystallization stage, the primary crystallization product is （Co, Fe）21Ta2B6 crystal, and the values of Hc and Ms increases gradually with increasing of a. Along with the development of crystallization, the values of Hc and Ms increase sharply when （Co, Fe）B and （Co, Fe）3B2 crystals precipitate. Under the non-isothermal crystallization conditions, the value of Ms increases monotonously with increasing of the stopping temperature, but the increase amplitude is very small. The value of Hc varies substantially with increasing of the stopping temperature, and the varying is non-monotonous. Within the temperature range of the first crystallization peak, the value of Hc increases monotonously with increasing of the stopping temperature. When the stopping temperature is higher then that of ending of the second crystallization peak, the value of Hc decreases drastically. When the stopping temperature increases from 968 to 1153 K, the values of Ms and Hc increase from 61.74 to 67.7 A·m^2/kg and from 267.6× 79.6 to 416.2× 79.6A/m, respectively. The Hc value decreases to 152.2 × 79.6 A/m when stopping temperature is up to 1273 K.