交換耦合作用
田宗軍2， 彭 坤2，宋曉平1， 都有為2
(1. 西安交通大學 理學院材料物理系， 西安 710049；
2. 南京大學 物理系， 南京 210093)
摘 要: 用熔體快淬法制備了高性能納米雙相耦合Nd2Fe14B/α-Fe磁體，研究了快淬速率對其微結構和交換耦合作用的影響。 實驗結果表明， 控制快淬速率在12m/s時， 可直接得到顯微組織均勻， α-Fe相粒子細小且均勻分布的納米雙相耦合Nd2Fe14B/α-Fe磁體。低溫退火消除由快速凝固帶來的成分不均勻性后， 強烈的鐵磁交換耦合作用導致其最高磁性能為： iHc=432.2kA/m, Jr=1.08T, (BH)max=115kJ/m3。 快淬速率提高，非晶相體積分數(shù)增加， 在高溫晶化熱處理時軟硬磁相析出不均勻， 個別α-Fe相粒子奇異長大， 尺寸達到100nm左右，這不利于軟硬磁相間的交換耦合作用， 有損磁性能。
關鍵字: 納米復合磁體; 交換耦合作用; 微結構;矯頑力
Nd2Fe14B/α-Fe magnets
XIE Guo-zhi2, TIAN Zong-jun2, PENG Kun2,
SONG Xiao-ping1, DU You-wei
（1. Department of Physical Materials, School of Science, Xi’an Jiaotong University,Xi’an 710049, China;
2. Department of Physics, Nanjing University, Nanjing 210093, China）
Abstract:Nanocomposite Nd2Fe14B/α-Fe magnets are synthesized by melt-spinning a Nd8Fe86B6 alloy and the effect of wheel speed on the microstructure and exchange coupling interaction is investigated. The results show that there is an optimum wheel speed about 12m/s at which a homogeneous Nd2Fe14B/α-Fe microstructure with fine α-Fe grains is developed directly from the melt. After low temperature annealing, the non-uniform composition from amorphous is eliminated and the magnetic properties can increase. The maximum magnetic properties are: iHc=432.2kA/m, Jr=1.08T, (BH)max=115kJ/m3. However, higher wheel speed leads to the appearance of amorphous phase and its volume fraction increases with the increase of wheel speed. These result in a Nd2Fe14B/α-Fe structure with large α-Fe grains after a subsequent crystallization annealing, which deteriorates the exchange-coupling between Nd2Fe14B phase and α-Fe phase and decrease its magnetic properties.
Key words: nanocomposite magnets; exchangse coupling interaction; microstructure; coercivity
