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.     

微波与常规方式热处理对Nd2Fe14B/α-Fe纳米交换耦合磁体的作用比较

研究了微波辐射对几种磁性材料的作用 微波的作用决定于材料的种类、形状、大小以及气体压力 与传统的热处理方式相比 ,微波热处理具有显著的特点和优势 ,即其能量利用率很高 ,加热迅速而晶粒生长有限 经微波处理 ,纳米复合永磁体具有明显的剩磁增强作用且表现为单相行为 研究表明 ,金属并非总是微波的反射体     

退火温度对Nd4.2Dy0.8Pr4Fe85Nb1B5纳米复合材料磁性能的影响

用熔体快淬和晶化处理的方法制备了Nd4.2Dy0.8Pr4Fe85 Nb1B5纳米复合材料,研究了退火温度对材料磁性能的影响.结果表明,经不同退火温度进行退火处理得到的Nd4.2 Dy0.8Pr4Fe85Nb1B5纳米复合材料的磁性能不同,在580℃下退火处理3 min得到的样品具有最佳磁性能,即Hci=6787.0 ...     

V含量对Fe74.7—xCu0.8Nb2VxSi11.5B11纳米软磁合金结构及性能的影响

在室温下,用Ｍｏｓｓｂａｕｅｒ谱和透射电子显微镜（ＴＥＭ）考查了纳米晶Ｆｅ７４．７－ｘＣｕ０．８Ｎｂ２ＶｘＳｉ１１．５Ｂ１１（ｘ＝１．２,１．５,２．０）合金的显微组织。研究了Ｖ对α－Ｆｅ（Ｓｉ）晶粒的体积分数、平均直径、α－Ｆｅ（Ｓｉ）中的Ｓｉ含量以及合金性能的影响,对实验结果作了初步的定性解释。     

块体SmCo7/Nd2Fe14B异质纳米复合永磁体的微结构和磁性能

采用高压热压缩变形技术对高能球磨的SmCo基非晶-纳米晶粉体与商用的Nd-Fe-B纳米晶粉体的混合物冷压块进行变形处理,成功制备出块体各向异性SmCo₇/Nd₂Fe₁₄B异质纳米复合永磁体。通过X射线衍射仪（XRD）、透射电子显微镜（TEM）以及振动样品磁强计（VSM）对块体SmCo₇/Nd₂Fe₁₄B异质纳米复合永磁体的微结构和磁性能进行分析研究得出：所制备磁体的微结构由SmCo₇/Nd₂Fe₁₄B纳米晶区域组成,且SmCo₇/Nd₂Fe₁₄B纳米晶具有沿其（00l）方向（平行于压力方向）的择优取向;磁体具有明显的磁各向异性,室温下沿压力方向具有16 MGOe的最大磁能积;磁体具有较好的温度稳定性,其矫顽力温度系数β_{（RT-250℃）}=-0.26%℃^-1。研究结果表明,所制备磁体具有较高的潜力,可应用于国防军工、轨道交通等科技领域。     

退火温度对800MPa级C-Si-Mn-Cr系冷轧双相钢组织及力学性能的影响研究

以一种低成本的800 MPa级C-Si-Mn-Cr系冷轧双相钢为研究对象,对退火温度对其组织和力学性能的影响规律进行了研究,结果表明:实验钢在760℃退火时,再结晶不充分,残留少量变形组织和未溶碳化物。770℃以上退火时再结晶比较充分,组织为铁素体、马氏体和少量贝氏体的复合组织,随着退火温度的升高抗拉强度与延伸率逐渐降低,而屈服强度与屈强比逐渐升高,n值随退火温度的升高先升高后降低在790℃达到最大值。     

V含量对Fe_(74.7-x)Cu_(0.8)Nb_2V_xSi_(11.5)B_(11)纳米软磁合金结构及性能的影响

在室温下,用Mossbauer谱和透射电子显微镜（TEM）考查了纳米晶Fi(74.7-x)Cu(0.8)Nb2VxSi(11.5)B(11)（x=1．2,1．5,2．0）合金的显微组织．研究了V对α-Fe（Si）晶粒的体积分数、平均直径、α-Fe（Si）中的出含量以及合金性能的影响,对实验结果作了初步的定性解释．     

正火加热温度对非调质钢30Mn2V显微组织及性能的影响

以非调质钢30Mn2V为研究对象,分析了正火温度对奥氏体晶粒尺寸与室温显微组织及冲击韧性的影响。结果表明:在亚临界区附近正火,缓慢冷却,可使其冲击韧性大幅度提高,U型缺口冲击值αku可达120J/cm2以上。主要原因是晶粒细化、铁素体含量增多、组织均匀化和珠光体形态变化等。     

磁参数对六角铁氧体RAM温度稳定性影响

从磁参数(饱和磁化强度,磁晶各向异性场)温度稳定性出发,对六角铁氧体RAM的温度稳定性进行了讨论;通过对M、W型六角铁氧体在温度t=18~100℃,频率f=8~12GHz时吸收率R(R~f)的温度稳定性和材料起始磁导率μi随温度的变化曲线(μi~t)的测试,得到单轴六角铁氧体材料R~f的温度稳定性优于平面六角铁氧体材料,并且和材料的μi~t变化规律吻合较好的结果。     

退火温度对TiO2及Nb掺杂TiO2薄膜的影响

采用溶胶-凝胶法在普通载玻片上制备了均匀透明的TiO2薄膜和掺Nb的TiO2薄膜,利用XRD,UV-VIS等手段,研究了退火温度对薄膜的结构、紫外-可见光区透射率、光学禁带宽度等性质的影响,并分析了掺杂Nb对TiO2薄膜晶体结构和光学性能的影响。实验结果表明:退火温度越高,薄膜生长取向越好,晶粒尺寸越大,光透过率越低;掺杂Nb后,能明显改善其结晶与生长,并降低其晶粒尺寸,透射率光谱吸收边缘产生蓝移现象。     

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…     

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     

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。     

Nd2Fe17 nanograins effect on the coercivity of HDDR NdFeB magnets with low boron content

Relationships between the coercivity of hydrogenation disproportionation desorption recombination(HDDR) Nd12.5Fe81.5-xCo6Bx bonded magnets and boron content were investigated.Nd2Fe17 phase with planar magnetic anisotropy is present in the microstructure when x= 4at%-5.88at%,which does not reduce the coercivity of the bonded magnets.High-resolution transmission electron microscopy(TEM) images show that Nd2Fe17 phase exists in the form of nanocrystals in the Nd2Fe14B matrix.There is an exchange-coupling interaction between the two phases so that the coercivity of HDDR Nd12.5Fe81.5-xCo6Bx bonded magnets is hardly reduced with a decrease in boron content.     

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.     

Nd8-xDyxFe82Co6B4纳米复合永磁材料的磁性能

针对NdFeB纳米复合永磁材料的矫顽力偏低的现状,采用熔体快淬法制备了Nd8DyxFe82Co6B4（x=0,0．4,0．8,1．2,1．6）纳米复合永磁材料,研究了Dy和Co的添加对NdFeB纳米复合永磁材料的磁性能的影响．研究结果表明,Dy的添加可提高材料的各向异性场,提高矫顽力,但是Dy元素的添加使材料的剩磁降低,结晶温度升高,因此添加量不宜过多;复合添加Co原子不仅可以提高材料的剩磁和矫顽力,而且可以弥补只添加Dy元素使材料的结晶温度升高的缺陷．在最佳的热处理条件下,Dy含量x=0．8时的样品表现出最佳的磁性能,矫顽力jHc=524kA／m,剩磁Br=1．11T,最大磁能积（BH）max=158kJ／m^3．     

Enhancement of magnetic properties and thermal stability of nanocrystalline （NdDyTb）12.3（FeZrNbCu）81.7B6.0 alloy with Co substitution

The major drawbacks of Nd-Fe-B magnets are relatively low Curie temperature and poor thermal stability. Ribbons with the near stoichiometric 2:14:1 composition of Nd_(10.8)Dy_(0.75)Tb_(0.75)Fe_(79.7-x)Co_xZr_(0.8)Nb_(0.8)Cu_(0.4)B_(6.0)(x=0, 3, 6, 9, 12, 15) were prepared by rapid quenching and subsequent heat treatment. The effect of Co element on the magnetic properties, thermal stability, and microstructure of the ribbons was systematically studied by vibrating sample magnetometer(VSM), thermal magnetic analysis, atomic force microscopy (AFM), and transmission electron microscopy (TEM).It was found that Co substitution was significantly effective in improving the magnetic properties and the thermal stability of nanocrystalline ribbons. Although the intrinsic coercivity decreased from 1308.7 kA/m for x=0 to 817.4 kA/m for x=15, the remanence polarization and maximum energy product increased from 0.839 T and 116.5 kJ/m~3 for the Co-free samples to 1.041 T and 155.1 kJ/m~3 for the 12at% Co-substituted samples,respectively.About 10 K increase in Curie temperature was observed for the 2:14:1 phase with lat% Co substitution. The absolute values of temperature coefficients of induction and coercivity were significantly decreased with Co substitution, which may be attractive for high operational temperature applications. The microstructure of nanocrystalline ribbons was slightly refined with Co substitution.     

Nd－Fe－B合金中2－14－1相和Nd_2（Fe，Co）_（14）B的研究

研究了Ｎｄ２Ｆｅ（１４）Ｂ和Ｎｄ２（Ｆｅ，Ｃｏ）（１４）Ｂ合金的穆斯堡尔谱和显微组织．主要研究了Ｎｄ２Ｆｅ（１４）Ｂ在５００℃时的显微组织及Ｎｄ２（Ｆｅ，Ｃｏ）（１４）Ｂ中Ｆｅ原子占有概率的穆斯堡尔谱面积对Ｃｏ浓度的影响。     

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.