Effect of zirconium content on exchange coupling and magnetization reversal of nanocrystalline Nd_(12.3)Fe_(81.7-x)Zr_xB_6 alloy

The effect of Zr content on exchange coupling and magnetization reversal of the Nd12.3Fe81.7-xZrxB6(x=0-3.0) ribbons was systematically investigated.Interaction domains were imaged by magnetic force microscopy(MFM).The strength of interactions determined byWohlfarth's analysis increased first with Zr content x increasing,reached the maximum value at x=1.5,and then decreased with x further increasing.Initial magnetization curves and dependence of coercivity and remanence on applied magnetic field showed that...     

烧结钕铁硼永磁材料产业现状与挑战

一、烧结钕铁硼永磁材料的发展现状烧结钕铁硼永磁材料(以下简写为"S-NdFeB永磁材料")是一种能量密度很高的贮能器,利用它可以高效率地实现能量和信息的相互转换,而它本身的能量却并不消耗。NdFeB永磁材料的出现有力地推动了高新技术     

添加Dy和Nb的纳米复合Pr2Fe14B/α-Fe永磁合金结构和磁性

研究了添加Dy和Nb对纳米复合Pr₂Fe₁₄B/α-Fe永磁合金形成,组织结构及磁性的影响。结果表明:Pr₉Fe₈₅B₆非晶带的晶化过程,在α-Fe相初始晶化之后,出现Pr₂Fe₂₃B₃亚稳相,最终形成Pr₂Fe₁₄B+α-Fe两相组织.而添加Dy或同时添加Dy和Nb后晶化过程不出现亚稳相.添加Dy和Nb元素显著地提高了纳米复合永磁合金的磁性能。最终获得了磁性能为H_CI=702.4kA/m,B_r=1.03T,(BH)_max=132.6kJ/m³的纳米晶复合Pr₈Dy₁Fe₈₄Nb₁B₆永磁材料。     

回火过程中NdFeB系永磁合金的组织结构与磁性能

本文研究了NdFeB三元系永磁合金在恒温(773~1023K)回火过程中组织结构与性能的变化。实验结果表明:在回火初期(1~3min)矫顽力较快地提高,达到峰值后矫顽力又降低。回火温度越低,矫顽力达到峰值所需的时间越长,与烧结态相比,回火后矫顽力可提高1倍。回火前后合金的基体相没有变化,都是单相的,没有缺陷。回火过程仅是晶界,特别是晶界交隅处发生晶化与共晶转变。回火后矫顽力的提高与晶界的变化有关。     

还原—扩散法制取Nd-Fe-B系磁体

为了降低具有卓越永磁性的Nd-Fe-B磁体的制造成本,使之更快得到推广使用,本文研究了采用还原—扩散工艺路线,直接用Nd₂O₃作为原材料制取Nd-Fe-B磁体的方法、研究了基本组元Nd和添加元素CO、Al的含量对永磁性能的影响,成功地制造出Nd-Fe-B系永磁体。其中最佳性能为Br＝1.30 T,_MH_C＝0.46 MA/m,(BH)_max＝286.5 KJ/m³。实验结果还表明,氧在合金中起着有害作用,为了获得优异的磁性能,含氧量必须被控制在0.8%以下。     

Nb在单相Nd2Fe14B纳米晶合金晶化过程中的作用

利用X射线衍射、透射电镜和三维原子探针(three-dimensional atom probe,简称3DAP)等研究Nb在单相Nd2Fe14B纳米晶永磁合金的作用机制.结果表明,Nb的添加提高了合金的非晶形成能力和非晶的热稳定性,使得合金最佳晶化温度升高.三维原子探针分析表明,Nb一方面分布在非晶基体中,另一方面在淬态薄带中存在不同程度的偏聚,这些Nb富集区中存在大量B元素,稀土含量很少,甚至不存在,含有部分Fe元素.Nb富集区的存在阻碍新生Nd2Fe14B相的长大,使晶化后的组织细小且均匀,提高了合金的磁性能.     

Effect of cobalt substitution on magnetic properties and microstructure of nanocrystalline （NdDyTb）12.3（FeZrNbCu）81.7B6.0 ribbons

Effect of Co substitution and annealing treatment on the formation, magnetic properties and microstructure of (NdOyTb)12.3(FeZrNbCu)81.7CoxB6(x=0-15) ribbons prepared by rapid quenching and subsequent annealing was systematically investi-gated by means of differential scanning calorimeter (DSC), X-ray diffraction (XRD), high resolution scanning electron microscopy (HRSEM) and vibrating sample magnetometer (VSM). Phase analysis revealed single-phase material. The remanence polarization Jr and maximum en-ergy product (BH)max increased with increasing x from 0 to 12 and then decreased for x=lS. The intrinsic coercivity Hci of (NdDyTb)12.3 (FeZrNbCU)81.7-xCoxB6 ribbons optimally processed decreased from 1308.7 kA/m for x=0 to 817.4 kA/m for x=15. Optimum magnetic properties with Jr=1.041 T, Hci=944.9 kA/m and (BH)max=155.1 kJ/m3 were achieved by annealing melt-spun ribbon (x=-12) at 675℃ for 10 min. There was no significant influence of Co substitution on microstructure.     

Magnetic Properties and Phase Transformation of Tb1-xPrxFe1.96 （x=0 to 0.7） Compounds

In recent years,the fields of application of the(Tb,Dy)Fe2giant magnetostrictive materials,as ad-vancedfunctional materials,have become wider.Suchmaterials can be composed by pseudo-binaryRExRE′1-xFe2compounds that have the same sign ofmagnetostriction but the opposite sign of anisotropy,inorder to mini mize the magnetic anisotropy while stillmaintaining a large positive magnetostriction[1].Ac-cordingto Steven′s calculation,inthe magnetocrystal-line anisotropy and mangetostriction of rare…     

优化边界结构制备高矫顽力及高热稳定性烧结Nd-Fe-B磁体

用双合金工艺在(Nd0.75Dy0.10Tb0.15)12.69Fe79.01Co2.00Nb0.30B6.00近正分主合金粉中掭加质量分数为3%的富稀土辅合金(Nd0.75Dy0.10Tb0.15)25.00Fe21.50Co<21.50>Nb4.00Ga8.00Ti5.00Al8.00B7.00粉和3%的Dy2O3粉,成功制备出超高矫顽力和高热稳定性的烧结Nd-Fe-B磁体,内禀矫顽力Hci和最大磁能积(BH)max分别为3028 kA/m和254 kJ/m3,22-220℃剩磁和矫顽力的温度系数分别为-0.104%/℃和-0.356%/℃,260℃不可逆磁通损失Lhirr的绝对值仅为4%.微观组织分析表明:主相Nd2Fe14B晶粒边界光滑、平直,富Nd相连续均匀分布于主相晶粒周围;在Nd2Fe14B晶粒表层附近富含Dy,Dy2O3中的Dy通过扩散与富Nd相及Nd2Fe14B晶粒表层中的Nd发生置换,从而在界面附近增强了磁各向异性.在此基础上,进一步提出了制备高矫顽力烧结Nd-Fe-B磁体中Dy的理想分布示意图.