纳米晶复合Nd9.5Fe79-xCo5NbxB6.5(x=0, 1, 2, 3)永磁合金的微结构和磁性能

Microstrucuture and magnetic properties of nanocomposite Nd9.5Fe79-xCo5NbxB6.5 (x=0, 1, 2, 3) permanent alloys

摘要:

利用X射线衍射（XRD）、振动样品磁强计（VSM）、透射电子显微镜（TEM）和三维原子探针（3DAP）等研究了Nb元素对纳米晶复合Nd9.5Fe79-xCo5NbxB6.5(x=0, 1, 2, 3)永磁合金微结构和磁性能的影响。结果表明，随着Nb元素的增加，合金的剩磁Jr首先增加，在Nb含量为1at%时达到最大值0.94T，继续增加Nb元素后，合金的剩磁开始下降；矫顽力iHc则随着Nb元素的增加逐步增加，当Nb含量超过2at%后，增加幅度变缓；合金的最大磁能积(BH)max随着Nb元素的增加先增加后降低，纳米晶复合Nd9.5Fe77Co5Nb2B6.5合金具有最优的综合磁性能，即Jr＝0.91T，iHc=663kA/m，(BH)max=120kJ/m3。Nb元素在合金的晶化过程中富集于晶间形成NbFeB相，有利于细化晶粒尺寸，从而提高合金的磁性能。

Abstract:

Nanocomposite permanent magnets have been extensively researched because of their unusually high remanence, high energy products and low cost, but little research has elucidated the underlying mechanism for microstructure improvement. Nanocomposite Nd9.5Fe79-xCo5NbxB6.5(x=0, 1, 2, 3) alloys were prepared by melt-spinning at a rate of 18m/s cooperating with subsequent annealing. The effects of Nb content on microstructure and magnetic properties for the alloys have been studied by XRD, VSM, TEM and 3DAP. The results shown that the Jr firstly increases with increasing Nb content from 0.92T up to 0.94T at x=1, then decreases obviously with further Nb addition. The iHc increases monotonically and then remains relatively lower increasing ratio. The (BH)max appears to increase from 104kJ/m3 at x=0 to a maximum of 120kJ/m3 at x=2, then decreases sharply. An intergranular NbFeB phase with a chemical composition near the Nb: Fe: B stoichiometry of 26: 48: 26 between the Nd2Fe14B interfaces was found for Nd9.5Fe77Co5Nb2B6.5 by 3DAP technique, which provides direct evidence of magnetic properties improvement.