热变形温度对Nd_(14)Fe_(80)B_6磁体矫顽力的影响研究

Effects of deformation temperatures on coercivity of Nd_(14)Fe_(80)B_6 die-upset magnets

使用X射线衍射、扫描电镜和磁滞回线仪等研究热变形温度、平均片状晶长度、单畴晶粒占比、平均片状晶厚度对热变形Nd_(14)Fe_(80)B_6磁体矫顽力的影响。结果表明,当Nd_(14)Fe_(80)B_6热变形温度超过其富稀土晶界相熔点150~170K后,磁体矫顽力从737kA/m降低到355kA/m。热变形Nd_(14)Fe_(80)B_6磁体统计平均片状晶长度L为320~500nm,单畴晶粒占比0.52~0.26,多畴晶粒的增加是热变形磁体矫顽力下降的原因。随着热变形温度的增加、变形时间的延长,平均片状晶厚度增长速度快于平均片状晶长度,对应热变形磁体矫顽力的下降。若降低变形温度在富稀土晶界相熔点附近有望提高磁体的矫顽力。

Effects of deformation temperatures,average platelet-grain length,single domain grain ratio and average thickness of platelet grain on coercivity of Nd14Fe80B6 die-upset magnets were investigated with X-ray diffraction,scanning electron microscopy and hysteresis loop instrument.The results show that when Nd14Fe80B6 die-upset temperature is 150-170 K above the melting point of its rich-rare-earth boundary phase,the coercivity of magnets decreases from 737 to 355 kA/m.The average platelet-grain length ranges from 320 to 500 nm and single domain grain ratio changes from 0.52 to 0.26.The increase of multi domain grains is the main cause of the coercivity decreasing.As the deformation temperature increasing or deformation time prolonging,the thickening velocity is higher than the length increasing speed of the platelet grains,resulting in the decrease of coercivity.If the deformation temperature is reduced near to the melting point,the coercivity of the die-upset magnets would be improved.