添加Co对Nd2Fe14B/α-Fe双相纳米晶永磁材料熔炼、快淬和晶化过程影响的研究

采用熔体快淬法制备了Nd2(FeCo)14B/-Fe双相纳米晶永磁材料,利用XRD、SEM和TEM方法研究加入Co元素对该材料铸态、熔体快淬以及晶化过程中微观组织和物相转变规律的影响.确定以40m/s的钼辊线速度熔体快淬实现较为理想的非晶化、在750℃下保温0.5h的晶化工艺下可以获得50nm左右的较为理想的显微组织.     

熔体快淬法制备纳米复合磁体Pr10Fe85B5的工艺研究

通过熔体快淬法将Ｐｒ１０Ｆｅ８５Ｂ５合金在三种不同辊速下制备成微晶或非晶薄带,晶化热处理后得到纳米复合磁体,研究了辊速条件及晶化温度对纳米耦合磁体硬磁性能的影响,获得了高矫顽力的纳米复合磁体。     

快淬纳米复合Nd9Fe80Co4Nb1B6永磁合金相结构与磁性能研究

利用X线衍射仪、振动样品磁强计等测试手段研究了纳米复合Nd9Fe80Co4Nb1B6合金的相结构与磁性能,结果表明:淬速为20 m/s的合金,经710℃退火处理后,合金软硬磁性相的晶粒尺寸细小,两相之间具有较强的交换耦合作用,合金具有优良的综合磁性能,即剩磁为0.95 T,矫顽力达到540 kA/m,最大磁能积为112 kJ/m3.选择适当的快淬速度有利于改善退火后合金的相结构,提高合金的综合磁性能.     

晶粒取向对Nd-Fe-B烧结磁体磁性能的影响

对（NdDy)15(FeCO)78B7基一系列不同工艺条件下制取的取向度不同的烧结磁体,用X－射线衍射和磁性测量来分析永磁体织构和取向度与反磁化过程的关系,用DGY－2型永磁测量仪测试磁体退磁曲线,结果表明,磁体反磁化过程中,随磁体取向度A增加,J－H退磁曲线线性度提高,同时斜度变小并越来越接近水平线,膝部也越接近直角,剩磁Br线性提高,但内禀矫顽力有所下降,微观晶粒易轴对外磁场有各种取向,取向度是它们平均值的 cos(θ）函数,取向不同的晶粒,在反磁场下磁化强度变为零所对应的临界场H0不相同时,矫顽力也就不相同,大块材料的矫顽力实际上是各晶粒对应的临界场的统计平均值,因此,由退磁曲线与取向度的关系可以大致得出反磁化过程的各种信息。     

复合永磁合金（Nd—Fe—B系）快淬带的EDS研究

利用X-Ray能谱仪分析了两种双相复合永磁合金快淬带的成分形貌。结果表明添加Dy的Ca具有改变合金快淬带组织形貌的作用并有可能影响其结构。     

Dy^3＋掺杂对Fe3O4纳米粒子磁性能的影响

为提高Fe3O4纳米粒子的磁性能，研究了Dy^3＋掺杂对Fe3O4纳米粒子宏观磁性及粒径的影响。适量的掺杂可使Fe3O4粒子的粒径增大，饱和磁化强度提高。过量的掺杂不会引起粒径的进一步增大，但会引起饱和磁化强度的下降。在反应温度为55℃，搅拌转速900r／min，反应时间1．5h，掺镝量为12．17％的条件下，用化学共沉淀法制备出平均粒径为18．6nm、饱和磁化强度可达168．73mT的镝铁氧体粒子。     

添加钬的钕铁硼烧结磁体的结构与磁性能

在工业生产线上制备（33-X）（Pr-Nd）-xHo-64．90Fe-0．20Cu-0．75Al-1．15B（wt％,x=0、1、3、5）烧结磁体,分析了其显微组织、取向度、磁性能与钬添加数量的关系。结果表明,添加钬制备的钕铁硼烧结磁体,其取向度提高;磁体显微组织致密,富钕相在主相晶粒边界的分布比较均匀;磁体内禀矫顽力明显上升,而剩磁小幅度下降。通过优化合金成分设计与改进工艺过程控制,实现了45M性能档次的Pr-Nd-Ho-Fe-Cu-Al-B烧结磁体的批量生产。     

非传统热处理对纳米复相Nd2Fe14B/α-Fe永磁体磁性能的影响

为改善纳米复相Nd2Fe14B／α-Fe永磁合金微结构以提高磁性能，用熔体块淬和晶化热处理的方法制备纳米复相Nd2Fe14B／α-Fe永磁体，研究快速热处理、磁场热处理及动态晶化热处理等非传统热处理对Nd10.5Fe76.4 Co5Zr2B6.1永磁体组织结构和磁性能的影响。采用XRD、DTA、AFM、TEM等方法对合金的组织结构、晶化行为进行研究。结果表明：与传统热处理相比，非传统热处理不仅可促进快淬NdFeB粉末的品化，降低晶化温度，缩短晶化时间，而且能细化晶粒，增强晶粒间磁交换耦合作用，提高磁性能。Nd10.5Fe76.4Co5Zr2B6.1合金快淬粉末在685℃经6min动态晶化热处理后制得的粘结磁体获得最佳磁性能，剩磁Br为0．684T，内禀矫顽力Hej为685kA／m，磁感矫顽力Heb为439kA／m，最大磁能积(BH)m为79kJ／m^3。     

溶液酸度对磁性活性炭吸附性能和磁性能的影响

以太西无烟煤为原料、Fe3O4为添加剂制备煤基磁性活性炭,用不同浓度的盐酸溶液浸泡,测定酸液浸泡前后活性炭的碘值和亚甲蓝值,采用X射线衍射仪和振动样品磁强计分别测定、表征活性炭中含铁化合物的组成和磁性能.结果表明,溶液酸度对磁性活性炭的吸附性能和磁性能均有影响,当溶液酸浓度达到1mol/L时,磁性活性炭浸泡后的碘值提高了7.9%、达732.49mg/g,比磁化系数从259×10-7 m3/kg降低到7.16×10-7 m3/kg,但仍能采用磁场分选回收;当溶液酸浓度达到2mol/L时,磁性活性炭完全失磁.     

Zr对Nd2Fe14B/α-Fe快淬纳米复合永磁材料的影响

主要研究了Zr对Nd2Fe14B/Fe快淬纳米复合永磁材料的影响.研究发现,Zr元素的添加提高了快淬薄带的非晶热稳定性,晶化处理后的矫顽力和磁滞回线的方形度.三维原子探针分析发现,快淬薄带晶化后Zr在硬磁性相内部以及晶粒之间分布不均匀,有利于细化晶粒、提高的矫顽力以及改善磁滞回线的矩形度.     

纳米复合Nd2Fe14B/α Fe磁体中晶粒的随机各向异性

以Nd2Fe14B/α Fe为例，研究了球状纳米晶粒尺寸对复合磁性材料有效随机各向异性的影响. 结果表明，材料的有效随机各向异性常数〈Keff〉随软磁性晶粒尺寸Ds的增加而减小，随硬磁性晶粒尺寸Dh的增加而增大.要使复合磁性材料获得较大的各向异性(矫顽力),Ds应尽量减小(10?nm左右), Dh尽量增大.为使材料具有高的磁能积,Dh应大于10?nm, Ds在10?nm左右. 关键词：有效随机各向异性；纳米晶粒；纳米复合材料；交换耦合相互作用     

The structure and properties of Fe3O4／P （NaUA-St-BA）magnetic composite nano particles

Fe3O4/P (NaUA-St-BA) core-shell composite micro spheres were in situ prepared by soapless polymerization of styrene and butyl acrylate, with Fe3O4 magnetic colloidal particles coated with NaUA. The results of IR and XRD analysis demonstrated that the desired polymer chains have been covalently bonded to the surface of Fe3O4 nano particles. The morphology analysis by TEM confirmed that the composite particles have the core-shell structure and a relatively uniform diameter of about 100nm. The magnetic properties of the obtained composite latex particles were measured by VSM and found that they exhibited super paramagnetic properties.Finally, the prepared magnetic composite particles latex is stable for several months.     

Effect of Dy substitution on the microstructure and magnetic properties of nanograin Nd-Fe-B single-phase alloys

Nanocrystalline single-phase alloys with the nominal compositions (at%) of Nd12.3-xDyxFe79.7Zr0.8Nb0.8Cu0.4B60 (x=0, 0.5,1.5, and 2.5) were prepared by melt-spinning and subsequent annealing. X-ray diffraction analysis shows that the as-spun ribbons were mainly com-posed of the amorphous phase. A slight content of Dy stabilizes the amorphous phase during annealing treatment. The grain size becomes smaller and the coercivity of the annealed ribbon is gradually improved with the increase of Dy content. Excessive Dy is harmful to the re-manence. It is found that no intergranular phase exists between the grains by high-resolution transmission electron microscopy, and the grain boundaries are crystallographically coherent in the optimally annealed sample. The optimum magnetic properties of remanence (Jr=1.09 T), coercivity (Hci=1048 kA/m), and maximum magnetic energy product ((BH)m=169.5 kJ/m3) are obtained from the x=0.5 ribbon in a post heat-treated state (700℃, 10 min).     

纳米Cu粉对Nd_2Fe_(14)B磁性材料性能的影响

为了提高磁性材料的耐腐蚀性和力学性能,采用二元合金法制备了Nd2Fe14B磁性材料.利用X射线衍射仪、扫描电子显微镜、粒度分布仪和磁性材料测试设备分别对样品进行了性能检测.结果表明,添加纳米Cu粉后,Nd2Fe14B磁性材料的性能得到了明显的改善.当纳米Cu粉的质量分数为0.25%时,样品的剩磁、矫顽力、磁能积均得到了不同程度的提高;样品的晶界十分清晰,晶粒尺寸趋于均匀化;样品的耐腐蚀性能得到了明显的改善,且样品在0.005 mol/L的H2SO4溶液中腐蚀96 h后的质量损失仅为0.021 7 g/cm3.     

Effect of Cu doping and annealing treatment on the microstructure and magnetic properties of nanocrystalline single-phase Nd-Fe-B alloys

The effects of Cu addition and annealing treatment on the magnetic properties and microstructure of Nd12.3Fe81.7-xCuxB6 (x=0-1.2) ribbons melt-spun and annealed were systematically investigated by the methods of vibrating sample magnetometer (VSM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Optimum magnetic properties were achieved by annealing melt-spun Nd12.3Fe81.5Cu0.2B6 ribbons at 550°C for 15 min, which only contained Nd2Fe14B phase. The remanence, coercive force, and maximum ...     

Fabrication and magnetic properties of Sm3(Fe,Ti)29Nx/α-Fe dual-phase nanocomposite permanent magnetic material

Sm3(Fe,Ti)29Nx/α-Fe dual-phase nanometer magnetic material was fabricated through rapid solidification, crystallization and nitridation of Sm-Fe (Ti) alloy. The effect of combination of rapid solidification and Ti alloy addition on the phase formation and microstructure of the Sm-Fe alloy is investigated in this paper. The microstructure of amorphous phase and dual-phase nano-grain crystals before and after crystallization annealing were observed using a high-resolution transmission electron microscope (HREM). The dual-phase nano-grains after annealing were compacted together with a clear interface with the direct exchange-coupling mechanism. Different annealing processes were used to examine the melt-spun alloy. Comparison of the images of SEM showed that annealing at 750℃ for 10 min was most suitable to get homogeneous and nano-grains. No obvious kink was detected in the second quadrant of the hysteresis loop like a single hard magnet, and strong exchange coupling was found between hard magnets and soft magnets.     

Sm2Fe17N2.9永磁体的制备及磁性能的研究

利用球磨法制备Sm2We17N2．9粉体，利用X射线衍射仪、比表面积分析仪、扫描电镜、透射电镜、振动样品磁强计、交流初始磁化率测定仪等实验仪器和测量分析方法，对所制备的Sm2We17，及氮化物的磁性能进行了分析．实验结果表明：球磨法所制的样品质量配比数较为合理，样品在500℃氮化3h磁性能为最佳，主相为TH2Zn17的菱方结构，居里温度与氮化温度相差不大．     

FePt/Ag薄膜的结构和磁性

采用直流磁控溅射在SiO2〈0001〉基片上制备了FeAg和FePt/Ag薄膜,将其在不同温度下进行真空热处理,得到具有高矫顽力的L10-FePt颗粒膜。利用X射线衍射、振动样品磁强计、扫描探针显微镜对样品的结构、磁性、形貌进行了研究。结果表明:Ag元素的添加有效地降低了FePt薄膜的有序化温度,样品在300℃热处理时即发生有序化转变。随着热处理温度的升高,样品的有序化程度提高,矫顽力变大,样品表面粗糙度减小,形成了均匀的颗粒薄膜。     

Effects of yttrium on the formation and magnetic properties of bulk metallic glassy （Fe, Co）-B-Si-Nb alloys

The bulk metallic glassy (BMG) rods of [(Fe0.5Co0.5)0.72B0.192Si0.048Nb0.04]100-xYx (x=0-6) and [(FexCo1-x)0.72B0.192Si0.04]Nb0.04]96Y4 (x=0.5-0.8) were prepared by copper mold casting. The structure, thermal stability,and magnetic properties of the samples were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and vibrating sample magnetometer (VSM). Adding lat% to 6at% of yt-trium, the bulk glassy alloy rods of [(Fe0.5Co0.5)0.72B0.192Si0.048Nb0.04]100-xYx (x=0-6) with the diameter of 3 mm were not formed, and the sample with 4at% of yttrium showed less crystalline phase than others. When the Fe/Co atomic ratio was between 5:5 and 7:3, the bulk glassy alloy rods of [(Fe1-xCox)B0.192Si0.048Nb0.04]96Y4 (x=0.5-0.8) with the diameter of 2 mm were fabricated. In the (Fe, Co)-B-Si-Nb-Y BMGs, when the Fe content increased, the thermal stability, the supercooled liquid region, and the glass-forming ability (GFA) decreased, but the saturation magnetization (Ms) increased.     

Microwave absorbing properties and magnetic properties of different carbon nanotubes

The microwave absorbing properties and magnetic properties of as-grown Fe-filled carbon nanotubes (CNTs), annealed Fe-filled CNTs, and multi-walled CNTs were studied. Vibrating sample magnetometer results showed that the annealed Fe-filled CNTs have the weakest coercivity and strongest saturation magnetization among the three types CNTs, due to the presence of more ferromagnetic α-Fe nanowires. After annealing, the values increased to 291.0 Oe and 28.0 emu/g and the samples showed excellent microwave absorbing properties. The reflection loss was over 5 dB between 11.6 GHz and 18 GHz with a maximum value of 10.8 dB for annealed Fe-filled CNTs (1.1 wt%)/epoxy composite.