铜模吸铸Nd9Fe83-xTi4C4Bx(x=10～15)合金组织演化和磁性能的研究

Microstructures Evolution and Magnetic Properties of Copper Mold Suction Casting Nd9Fe83-xTi4C4Bx（x=10～15） Alloys

采用铜模吸铸及随后的退火处理制备了厚度为0.8 mm,成分为Nd9Fe83-xTi4C4Bx（x=10～15）的Nd2Fe14B/Fe3B型纳米复相磁体,对其组织演变和磁性能进行了研究。结果表明：在铸态合金中,x=10的合金微观组织主要由Nd2Fe14B,Fe3B,α-Fe和TiC相构成。而x=11～15的合金中除含上述各相外,还出现了Nd2Fe23B3相、未知相和非晶相,且随着B含量的增加,它们在合金中的相对含量有不同程度的增加;退火过程中,随着合金中亚稳相和非晶相的转化,Nd2Fe14B,Fe3B和α-Fe相对含量增加,但不同B含量合金的相结构变化差异明显,导致退火后磁体具有不同的磁性能。其中,x=12的合金在680℃退火5 min后获得了最佳磁性能：Br=0.63 T,iHc=98.12 kA·m^-1,（BH）max=22.79 kJ·m^-3。

The Nd2Fe14B / Fe3B type nanocomposite magnets of Nd9Fe83- xTi4C4Bx（ x = 10 ～ 15） alloys with the thickness of 0. 8 mm were prepared by copper mold suction casting and subsequent annealing. The microstructure evolution and magnetic properties of the magnets were studied. The results showed that the microstructure of as-cast Nd9Fe83- xTi4C4Bx（ x =10） alloy was mainly composed of Nd2Fe14B,Fe3B,α-Fe and TiC. In addition to the phases above,Nd2Fe23B3as well as an unknown phase,and an amorphous phase appeared in the microstructures of ascast Nd9Fe83- xTi4C4Bx（ x =11 ～15） alloys,and their relative contents in the alloys increased to different extent along with the increasing of the content of B. In the annealing process,with the conversing of metastable phases and amorphous phase,the relative amount of Nd2Fe14B,Fe3B and α-Fe in the alloys increased respectively. But obvious difference could be found in the microstructure transformations in the alloys of diverse B content,leading to the difference in their magnetic properties of the annealed alloys. For the Nd9Fe83- xTi4C4Bx（ x =10 ～15） alloys,the optimal magnetic properties of Br= 0. 63 T,iHc= 98. 12 kA·m^- 1,（ BH）max= 22. 79 kJ·m^- 3could be achieved when x = 12 annealing at 600 ℃ for 5 min.