熔体温度对快淬法制备纳米晶复合Nd8.5Fe77Co5Zr3B6.5合金微观结构和磁性能的影响

Effect of Melt Temperature on the Microstructure and Magnetic Properties of Nd8.5Fe77Co5Zr3B6.5 Nanocomposite Magnet

摘要:

将Nd8.5Fe77Co5Zr3B6.5合金熔化至不同温度后,以18 m/s的甩带速度快淬,对淬态条带进行了退火处理,分析了其微观结构和磁性能的变化。结果表明,熔体温度对淬态及其退火态合金的微观结构和磁性能可以产生重要影响,熔体温度为1210 °C时制备的快淬条带由Nd2Fe14B相和部分非晶相组成,具有一定的硬磁性；随着快淬时熔体温度的升高,淬态条带中非晶相的含量逐渐增加,其磁性逐渐转变为软磁性。几种合金经退火处理后均由大量Nd2Fe14B相与少量软磁相组成,熔体温度较低的合金退火后其晶粒尺寸较小,磁性能较好。熔体温度为1210 °C时制备的合金退火后磁性能最佳,内禀矫顽力Hci为559.2 kA/m,剩余磁化强度Br为0.98 T,最大磁能积(BH)max为127.8 kJ/m3。

Abstract:

Nanocomposite Nd8.5Fe77Co5Zr3B6.5 alloys were prepared by melt-spinning under different melt temperatures. The effect of melt temperature on the microstructure and magnetic properties of alloys was investigated. The results show that the melt temperature is a key factor that affects the microstructure and magnetic properties of as-quenched and also as-annealed alloys. The as-quenched alloys melt-spun at 1210 °C are composed of amorphous phase and Nd2Fe14B phase. The relative content of amorphous phase in as-quenched alloys increases as melt temperature increases. As-spun alloys with high content of amorphous phase show soft magnetic properties. Subsequent annealing of as-spun alloys initiates the formation of nanocrystalline Nd2Fe14B phase and precipitation of a small amount of soft magnetic phase. Alloys with finer microstructure and more favorable magnetic properties are obtained by crystallizing the as-quenched alloys melt spun at lower melt temperature. The as-annealed alloys melt-spun at 1210 °C shows optimum magnetic properties with an intrinsic coercivity of 559.2 kA/m, remanence of 0.98 T, and maximum energy product of 127.8 kJ/m3.