添加Mo元素对Fe40Co40Zr9B10Ge1合金晶化过程和磁性能影响

采用单辊快淬法制备Fe40Co40Zr9B10Ge1和Fe40Co40Zr5Mo4B10Ge1两种非晶合金,并在不同温度下对其进行热处理。利用XRD和VSM两种仪器对合金的微观结构和磁性能进行测试分析,研究Mo添加对Fe40Co40Zr9B10Ge1合金晶化过程和磁性能的影响。结果表明,两种合金在晶化初期均有α-Fe(Co)相从非晶基体析出,但高温热处理后的晶化产物不同,Mo添加减少了高温金属化合物的含量。低于675℃热处理,Mo添加降低了合金晶化过程中析出α-Fe(Co)相的晶粒尺寸和合金的矫顽力。     

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。     

Fe3B添加量对Nd-Fe-B快淬薄带结构与磁性能的影响

通过在Nd2Fe14B合金中按Fe3B原子比同时添加Fe与B,研究了Nd15Fe77B8、Nd9Fe81B10、Nd4.5Fe77.0B18.5 3种合金薄带的结构与磁性能.试验发现,40 m/s的快淬速度使三种合金薄带中形成了较多的非晶相,而且随着合金中Fe3B添加量的增加,薄带的非晶形成能力增强、α-Fe与Fe23B6含量增加、Nd2Fe14B含量减少,磁性能单调降低.经680℃保温10 min退火处理后,3种薄带中的非晶相明显减少,Fe3B相消失,.α-Fe与Fe23B6含量随Fe3B添加量的增加而增加.其中,薄带中Nd2Fe14B晶粒约50 ～ 100 nm,而α-Fe晶粒一般小于50 nm.Nd15Fe77B8退火薄带更多地表现为单硬磁相特征;Nd9Fe81B10退火薄带中形成了α-Fe/Nd2Fe14B/Fe23B6三相交换耦合微结构,剩磁比达到了0.612,并获得最大的剩磁58.3 A· m2/kg;而Nd4.5Fe77.0B18.5薄带中Fe23B6与α-Fe含量太高,矫顽力太低而使剩磁增强效应不明显.     

Fe_(40)Co_(40)Zr_(10)B_9M_1(M=Cu,Ge,Ag)合金的热稳定性及微观结构研究

采用单辊快淬法制备Fe40Co40Zr10B9Cu1、Fe40Co40Zr10B9Ge1和Fe40Co40Zr10B9Ag1非晶合金薄带,并对3种合金在不同温度下进行热处理.利用差热分析仪(DTA)和X射线衍射仪(XRD)等测试手段对样品的热稳定性及微观结构进行研究.结果表明:Fe40Co40Zr10B9Cu1、Fe40Co40Zr10B9Ge1和Fe40Co40Zr10B9Ag13种合金的激活能分别为262.4、267.6和252.3 k J/mol,说明Cu元素、Ge元素和Ag元素的添加对合金的热稳定性影响不大,Ge元素的添加最有利于提高合金的热稳定性.3种合金的晶化过程相似:非晶→非晶+α-Fe(Co)→α-Fe(Co)+Zr Co3B2+Fe(Co)3Zr.     

Fe73.5Si13.5B9Cu1Nb3-xMox（x=1,2,3）非晶合金的晶化动力学研究

采用单辊熔体快淬法在大气环境中制备Fe73.5Si13.5B9Cu1Nb3-xMox（x=1,2,3）非晶合金薄带,利用差示扫描量热分析和X射线衍射分析进行非晶合金的晶化动力学研究,计算出Fe73.5Si13.5B9Cu1Nb3-xMox（x=1,2,3）非晶薄带的晶化激活能分别为349、262、332 kJ/mol,其Avrami指数分别为1.95、2.14和2.00。结果表明,随着升温速率的提高,Fe73.5Si13.5B9Cu1Nb3-xMox（x=1,2,3）非晶薄带的起始晶化温度和晶化峰值温度相应升高;以Mo部分替代Nb降低了非晶合金的晶化激活能;-αFe（Si）软磁相具有扩散控制的低维形核和生长的晶化机制,且形核率逐渐减小。     

热作用对喷射沉积Mg-7Al-1.5Zn-4.5Ca-1Nd合金坯组织的影响

采用喷射沉积方法制备了Mg-7Al-1.5Zn-4.5Ca-1Nd合金,通过对沉积态合金不同温度加热处理后试样的组织观察,分析了此合金的相变及组织演变特征。结果表明:喷射沉积坯晶粒细小,组织分布均匀,组织中含有α-Mg、Mg17Al12、MgZn2、Al2Ca和Ca2Mg6Zn3等相;当加热温度从350℃升到520℃时,喷射沉积坯组织有明显的变化,Mg17Al12相溶解,Ca2Mg6Zn3分解为Mg2Ca和MgZn2相,高温时析出了新相Mg12Nd;且硬度随着加热温度的升高而持续下降。     

Cu对Sm3(Fe,Ti)29Nx/α-Fe双相纳米耦合磁体磁性能的影响

通过对Sm10Fe84Ti6和Sm10Fe84Ti5Cu1两种合金采用甩带快淬、晶化、氮化等工艺处理,成功制备了Sm3(Fe,Ti)29Nx／α-Fe双相纳米耦合永磁复合材料．试验结果表明Sm10Fe84Ti6和Sm10Fe84Ti5Cu1两种合金经甩带后均主要由Sm3(Fe,Ti)29和α-Fe两种物相组成,但合金中α-Fe相的相对含量不同．两种合金氮化后的矫顽力和剩磁均在750℃晶化时达到最高值;Sm10Fe84Ti6合金氮化后的Sm3(Fe,Ti)29Nx和α-Fe晶粒细小,晶界平直,其磁滞回线具有单一永磁体的特性,硬磁相与软磁相能达到较好的直接交换耦合,具有较高的矫顽力和剩磁．而添加的Cu对晶界状态的影响对交换耦合作用起决定性因素,析出物聚集于晶界造成晶界的晶粒阻隔效应,导致晶界处交换耦合常数降低从而降低交换耦合作用,使得纳米磁体的剩磁和矫顽力都降低．     

不同Co含量对Fe_(80-x)Co_xZr_(10)B_9Cu_1(x=0,10,20,30,40)合金的热稳定性和微观结构的影响

采用单辊快淬法制备Fe80-xCoxZr10B9Cu1(x=0,10,20,30,40)系非晶合金.在不同温度下对其进行热处理.利用差热分析仪(DTA)和X射线衍射仪(XRD)等测试手段对样品的热稳定性和微观结构进行研究.研究结果表明:Fe80-xCoxZr10B9Cu1(x=0,10,20,30,40)五种合金的晶化激活能分别为318.15、304.49、226.75、386.97和267.03 kJ/mol.未添加Co元素的Fe80Zr10B9Cu1合金的热稳定性明显高于添加Co元素的合金.Co元素的添加改变了合金的晶化过程.     

700℃高温短时时效对ZG12Cr9Mo1Co1NiVNbNB铁素体耐热钢显微组织的影响

为了了解ZG12Cr9Mo1Co1NiVNbNB铁素体耐热钢在高温使用过程中的组织演化规律,本文采用透射电子显微镜和能谱仪等先进手段研究了高温时效对该钢组织的影响。研究结果表明：在700℃时效100h后,该钢的基体组织主要由马氏体板条,大量位错和析出相组成;析出相主要是Fe(Cr, Mo)23C6、VC、Fe2Mo型Laves相;大尺寸的Fe(Cr, Mo)23C6型碳化物主要分布于马氏体板条界和原奥氏体晶界,细小的VC型碳氮化物主要分布于基体, 且析出相的数量增加;在高温时效过程中,Fe(Cr, Mo)23C6的尺寸增大。VC颗粒尺寸变化不大,热稳定性比Fe(Cr, Mo)23C6好。     

快凝对MmNi5-x(CoMn)x合金电化学性能的影响

利用熔体淬冷法制备出不同速度下的4种合金薄带,研究了快凝对贮氢合金电化学性能的影响.合金的晶体结构采用XRD和SEM进行表征.结果显示,铸态和快凝合金都是单一的CaCu5相结构,快凝后的合金组织变得更加细密,晶粒变小而且更加均匀.电化学实验结果表明,快凝显著提高了合金的稳定性,但是降低了合金的放电容量和高倍率性能,铸态...     

Crystallization kinetics of amorphous Nd_(3.6)Pr_(5.4)Fe_(83)Co_3B_5 and preparation of α-Fe/Nd_2Fe_(14)B nanocomposite magnets by controlled melt-solidification technique

1　INTRODUCTIONNanocompositeexchangecoupledmagnetsconsistingofafinemixtureofhardandsoftmagneticphaseshaveat tractedmuchattentionforpotentialpermanentmagnetde velopment,sincetheycould ,byexchangecoupling[1] ,potentiallyprovideamaximumenergyproduct [(BH) max]inexcessof 80 0kJ·m- 3[2 ] .Uptonow ,manynanocom positemagnetsystems,includingNd2 Fe14 B/Fe3B ,R2 Fe14 B/Fe,R2 Fe14 C/Fe (R =Nd ,Pr) ,Sm2 Fe17Nx/Fe ,andSm2 (Fe,Si) 17Cx/Fe[3] ,havebeenextensivelystudied .Unfortunately,inprac…     

R(Fe,M)_(12)N_x新型稀土永磁研究

简要回顾了稀土永磁材料的发展历史.综述了R(Fe,M)_(12)N_x 1:12相稀土永磁的结构、性能、制备工艺以及间隙氮原子和各合金元素的作用.论证了NdFe_(10.5)V_(1.5)N_x和NdFe_(10.5)Mo_(1.5)N_x合金具有很大的永磁潜力.     

Anisotropic characteristic in HDDR Nd_(13)Fe_(80)B_7

The function of disproportionation and desorption stages of hydrogenation-disproportionation-desorption-recombination (HDDR) process in the formation of magnetic anisotropy was studied. The results showed that degree of anisotropy (DOA) of Nd13Fe80B7induced by appropriate HDDR process is comparable with that of Nd13Fe80-xB7Mx(M=Co, Zr or Ga), however, the moderate coercive force of Nd13Fe80B7 magnetic powder led to an undesirable (BH)max of 104 kJ/m3 in bonded magnet. Experiments demonstrated that a relatively short disproportionation time, combined with a high desorption temperature and slow desorption rate, during HDDR process is beneficial to anisotropy attainment, but HDDR Nd13Fe80B7 magnetic powder becomes isotropic if the disproportionation time is longer than a certain period. This phenomenon strongly indicated that the origin of anisotropy in NdFeB-type HDDR material is contributed by disproportionation stage. XRD (X-ray Diffraction) analysis and TEM (Transmission Electron Microscope) observatio     

Effect of annealing time on the exchange coupling interactions and microstructure of nanocomposite Pr7.5Dy1Fe71Co15Nb1Ba4.5 ribbons

The influence of annealing time on the magnetic properties and microstructure of nanocomposite Pr7.5Dy1Fe71Co15Nb1B4.5 ribbons was systematically investigated by the methods of vibrating sample magnetometer (VSM), X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). Interaction domains derived from strong exchange coupling interactions between hard and soft magnetic grains were imaged using magnetic force microscopy (MFM). Maximum remanence, intrinsic coercivity, and maximum energy product values were obtained in the ribbons annealed at 700℃ for 15 min, which were composed of Pr2(Fe, Co)14B, α-(Fe, Co), and slight Pr2(Fe, Co)17 phases. Although Jr, Hci, and (BH)max decreased gradually with further increase of annealing time, it is emphasized that comparatively high Jr and Hci and (BH)max were obtained in a wide annealing time period of 15 to 360 min. The shape of initial magnetization curves and hysteresis loops change as a function of annealing time, indicating different magnetization reversal routes, which can be fully explained by the corresponding microstructure.     

NdxFe94-xB6微波磁导率的研究

采用熔体快淬法制备成分为NdxFe94-xB6(x=9.5,10.5,11.5)的纳米复相Nd2Fe14B/α-Fe材料。研究了稀土Nd含量对该材料的微波磁导率和自然共振峰频率的影响。采用XRD、VSM、矢量网络分析仪等方法对材料相组成、微结构、静态磁性能及微波磁导率特性进行测试分析。结果表明:当Nd的原子百分含量由9.5%增加至11.5%,材料的自然共振峰频率由6.53 GHz增加至15.91 GHz,微波磁导率μ"max由1.59(x=9.5)降至0.56(x=11.5)。     

Influence of secondary carbide precipitation and transformation on abrasion resistance of a 3Cr15Mo1V1.5 white iron

The relationship between the secondary carbide precipitation and transformation of the 3Cr15Mo1V1.5 white iron and abrasion resistance was investigated by using optical microscope （OM）, transmission electron microscopy （TEM） and X-ray diffrac- tion （XRD）. The results show that the properties of secondary carbides precipitated at holding stage play an important role in the abrasion resistance. After certain holding time at 833 K subcritical treatment, the grainy （Fe, Cr）23C6 carbide precipitated and the fresh martensite transformed at the holding stage for 3Cr15Mo1V1.5 white iron improve the bulk hardness and abrasion resistance of the alloy. Prolonging holding time, MoC and （Cr, V）2C precipitations cause the secondary hardening peak and the corresponding better abrasion resistance. Finally, granular （Fe, Cr）23C6 carbide in situ transforms into laminar M3C carbide and the matrix structure transforms into pearlitic matrix. These changes weaken hardness and abrasion resistance of the alloy sharply.