单相纳米晶Nd12.3Fe79.2Nb2.5B6合金的交换耦合作用与显微组织

采用熔体快淬及晶化退火工艺制备了含铌单相纳米晶Nd12.3Fe79.2Nb2.5B6合金,研究添加Nb对单相Nd2Fe14B纳米晶合金的磁性能、交换耦合和微观结构的影响规律.结果表明:Nb的添加提高了合金的非晶热稳定性,使得合金最佳晶化温度升高;合金晶化退火后,Nb可使晶粒尺寸分布均匀,并得到单一Nd2Fe14B相;晶粒边界比较完整,存在共格、半共格或大角度晶界,但没有观察到晶界相.上述结构可有效提高合金的磁性能,增强交换耦合作用.通过对Nd12.3Fe79.2Nb2.5B6合金磁性能分析可知:650 ℃晶化退火10 min后的合金性能最佳,交换耦合作用最强.

Intergranular exchange coupling interaction and microstructures of nano-crystal Nd12.3Fe79.2Nb2.5B6 alloy

The effect of Nb on the magnetic properties, microstructures and exchange coupling interactions of Nd12.3Fe79.2Nb2.5B6 alloy prepared by melt-spinning and subsequent annealing were systematically studied. The results show that the addition of Nb improves the thermal stability of the as-spun amorphous ribbons, as well as improves the optimum crystallization temperature. The ribbons annealed at 650 ℃ are composed of only Nd2Fe14B phase with the grain size uniformly distributing, no intergranular phases are observed. The grain boundary can be almost perfect and coherent, semi-coherent or large angle grain boundary. Therefore, the comprehensive magnetic properties and intergranular exchange coupling interactions of the materials are strengthened. From the analysis of the magnetic properties of the alloy, it is found that, after annealed at 650 ℃ for 10 min, Nd12.3Fe79.2Nb2.5B6 alloy has the optimum magnetic properties and the strongest exchange coupling interactions.