Fe_(64-x)Co_xNd_7B_(25)Nb_4(x=0～40)块体合金的晶化过程和磁性能研究

CRYSTALLIZATION PROCESSES AND MAGNETIC PROPERTIESOF Fe_(64-x)Co_xNd_7B_(25)Nb_4(x=0～40) ALLOYS

采用铜模吸铸法制备了Fe64-xCoxNd7B25Nb4(x=0～40)块体合金,利用X射线衍射仪(XRD)、差示扫描量热仪(DSC)和振动样品磁强计(VSM)研究了该体系合金的非晶形成能力、晶化过程和磁性能。结果表明:Fe64-xCoxNd7B25Nb4(x=0～40)块体合金具有良好的非晶形成能力。在Co含量为0at%～40at%范围内,合金基本为非晶态。该系合金铸态时为软磁性,晶化处理后则表现为硬磁性。随着Co含量的不同,合金的晶化行为和晶化后的产物及对应的磁性能均有明显的变化。不含Co元素时,合金发生两级晶化反应;晶化过程中出现了亚稳相Fe23B6,随着退火温度的升高,Fe23B6分解为Fe3B和α-Fe相。添加Co元素后,合金只发生一级晶化反应。Co含量为20at%的合金在1 003 K退火后,内禀矫顽力高达1 164 kA/m。

Fe64-xCox Nd7 B25Nb4 （ x = 0 - 40） alloys were prepared by copper mold casting. The glass-forming ability, crystallization processes and magnetic properties were investigated by X-ray diffraction （XRD）, differential scanning calorimetry （DSC） and vibrating sample magnetometer （VSM）. The results showed that Fe64-xCOx Nd7 B25Nb4 （ x = 0 - 40） bulk alloys exhibited good glass-forming ability. When Co content reached 0at% -40at%, the alloys mainly consisted of amorphous phase. The as-cast alloys showed soft magnetic properties, while the alloys after crystallization treatment exhibited hard magnetic properties. The crystallization behavior, precipitated phases and magnetic properties of the alloys changed obviously with the contents of Co. The crystallization process for the Co-free alloy consisted of two steps. The metastable phase Fe23 B6 appeared during the crystallization, and decomposed into FegB and α-Fe phases after annealing at a higher temperature. However, for the alloy with Co addition, crystallization was completed in one step. When the Co content was 20at%, the value of intrinsic coercivity reached 1 164 kA/m after annealing at 1 003 K.