首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到18条相似文献,搜索用时 156 毫秒
1.
李腾  李卫  潘伟  李岫梅 《物理学报》2005,54(9):4389-4394
研究了高矫顽力型FeCrCo合金的磁性和微观结构.实验结果表明,适当的合金成分及热处理 条件可以明显提高FeCrCo合金的矫顽力.通过透射电镜、x射线衍射等手段得出结论:主体元 素含量的提高和微量元素的掺杂可以有效地控制相的组成,磁场热处理导致强磁性相和弱磁 性相的分离,回火后形成起磁硬化作用的调幅结构.该调幅结构中较大的两相成分差有利于 提高FeCrCo合金的矫顽力. 关键词: 矫顽力 调幅分解 磁场热处理 两相结构 成分差  相似文献   

2.
高矫顽力型FeCrCo合金相变化的穆斯堡尔谱研究   总被引:1,自引:0,他引:1       下载免费PDF全文
李腾  李卫  李岫梅 《物理学报》2005,54(9):4384-4388
通过穆斯堡尔谱、透射电镜、x射线和磁测量等手段研究了将普通FeCrCo合金中Cr,Co元素含 量提高、并加入Mo,Zr元素后合金矫顽力的变化,发现其值76kA/m比普通值40—52kA/m高50% 以上.对该合金不同热处理阶段的穆斯堡尔谱的测试表明,合金的微观结构与普通FeCrCo合 金有显著的不同.固溶处理后合金单相性好,不产生对磁性起破坏作用的γ相;磁场热处理 过程中,发生原子的重新排布,α2相开始出现,两相结构基本确定;分级回火 后,调幅 分解进行得更彻底,合金内部完全形成调幅结构,与低矫顽力合金相比,铁磁性的α1 相更容易形成. 关键词: 穆斯堡尔谱 调幅分解 磁超精细场 同质异能移  相似文献   

3.
利用电子衍射在正常凝固Al65Cu20Co15合金中观察到不属于Fibonacci序列的新的空位有序超结构相τ2327和τ35。衍射强度计算表明其堆垛方式分别为332323232,3323323323和3323323323323。 关键词:  相似文献   

4.
卢艳丽  陈铮  来庆波  张静 《物理学报》2009,58(13):319-S326
基于微观相场动力学模型,运用原子图像、平均长程序参数和平均成分偏离序参数,研究了Al浓度对Ni75Cr25-xAlx合金中L12相和D022相形核孕育期的影响以及孕育期与沉淀相析出顺序之间的关系.结果表明,L12相和D022相的形核孕育期不仅与Al浓度有关,而且与两相析出的先后顺序密切相关.当Al浓度小于7.5%时,先析出相为D022相,随着Al浓度的增大,D022相形核孕育期延长,后析出的L12相的形核孕育期也延长,L12相的原子簇?聚?速度加快;当Al浓度大于7.5%时,先析出相为L12相,随着Al浓度的增大,L12相的形核孕育期缩短,后析出的D022相形核孕育期也缩短.当Al浓度为7.5%时,L12相和D022相几乎同时析出,两者的孕育期没有明显的差别. 关键词: 形核孕育期 序参数 沉淀 微观相场模拟  相似文献   

5.
通过熔体快淬方法获得Pr(Fe1-xCox)2合金条带,经过X射线衍射、差示扫描量热计和磁性测量对其结构、磁性和热稳定性进行了研究.发现当Co的含量x大于0.2时才可能获得Pr(Fe,Co)2立方Laves相化合物.对Pr(Fe0.6Co0.4)2合金,在快淬速度为30m/s时,条带由Pr2(Fe,Co)17,Pr(Fe,Co)2和富稀土相组成;在速度为40m/s时,获得了几乎单相的Pr(Fe0.6Co0.4)2化合物,其居里温度为305℃;在速度为45m/s时,除了Pr(Fe0.6Co0.4)2化合物外,还存在少量的非晶相.Pr(Fe0.6Co0.4)2化合物在770℃以上发生分解.用40m/s快淬纳米晶粉胶粘磁体有大的磁致伸缩系数(λ=140×10-6)和高的硬磁性能(iHc=398kA/m). 关键词:  相似文献   

6.
采用直流溅射的方法,在Pt3Co合金靶上加贴Ni片,把(Pt3Co)1-xNix合金薄膜中非磁性原子与磁性原子的比率从3:1调制到1:1.通过高角X射线衍射谱和磁性的研究,发现<111>织构至少在0.33—0.50的Ni成分范围内不是引起垂直磁各向异性的主要原因.在此基础上研究了(Pt3Co)1-xNix合金薄膜的磁光特性.研究表明,适量Ni合金化(x=0.43)可以获得较低的(Pt3Co)1-xNix合金薄膜居里温度,同时保持较高的垂直磁各向异性、较大的矫顽力和蓝波长下较高的Kerr转角,从而为PtCoNi合金薄膜的实用化提供了实验参考. 关键词:  相似文献   

7.
运用微观相场法研究Ni75Al5.3V19.7合金沉淀过程中L12结构和D022结构反位缺陷发现:在沉淀初期,L12结构反位缺陷AlNi,VNi,NiAlD022结构反位缺陷VNi,AlNi关键词: 微观相场 反位缺陷 L12结构')" href="#">L12结构 D022结构')" href="#">D022结构  相似文献   

8.
Nd2(Fe1-xMnx)14B的低温内禀矫顽力   总被引:1,自引:0,他引:1       下载免费PDF全文
杨应昌  张晓东 《物理学报》1990,39(4):649-655
当x<0.5时,Nd2(Fe1-xMnx)14B可形成四方晶体结构,空间群为P42/mnm。在低温下,该赝三元化合物的大块铸态样品具有高矫顽力。此矫顽力不依赖于热处理等工艺过程,因此具有内禀性质。内禀矫顽力 iHc与样品的成分有关。Nd2(Fe1-xMnx)14B的起始磁化曲线具有传播场Hp,并且Hp的数值与 iHc接近。这表明内禀矫顽力是由畴壁钉扎造成的。研究了 iHc与温度的变化关系,并估算了钉扎位垒的强度。测量了Nd2(Fe1-xMnx)14B的居里温度和饱和磁化强度。在此赝三元化合物中,交换作用随Mn对Fe的替换而急剧降低。这使得畴壁厚度变窄。Nd2(Fe1-xMnx)14B的磁化和反磁化行为可用窄畴壁的特征来解释。 关键词:  相似文献   

9.
磁控溅射法制备的CaCu3Ti4O12薄膜   总被引:2,自引:0,他引:2       下载免费PDF全文
周小莉  杜丕一 《物理学报》2005,54(4):1809-1813
采用溅射方法成功地制备了CaCu33Ti44O1212薄膜, 用原子力显微镜、x射线衍射(XRD)仪和LCR分析仪对样品进行形貌、物相结构和介电性质的研究.XRD表明,薄膜比块体的晶 格常数小但晶格畸变较大;LCR测量结果显示,在相同温度下薄膜比块体的相对介电常数低 ,薄膜相对介电常数由低到高转变时对应的温度较高且激活能较大.分析表明:薄膜的相对 介电常数较低是样品中晶相含量较低、缺陷较多使内部阻挡层电容大量减小、致密度不高引 起的;薄膜中 关键词: 磁控溅射 3Ti44O1212')" href="#">CaCu33Ti44O1212 介电常 数 激活能  相似文献   

10.
用固态粉末烧结法配制样品,用X射线衍射及差热分析等方法研究并测定了LiIO3-Zn(IO3)2赝二元系的相图。该二元系内存在一新相LiZn(IO3)3。它有较大的倍频效应,具有离子导电性。用自编的由粉末衍射数据求单斜晶系的点阵参数的计算机程序成功地求出了该化合物的点阵常数。经过进一步修正,确定它属于正交晶系,α=8.08l?,b=8.729?,c=11.595?,z=4。并确定了化合物存在的成分范围和条件。 关键词:  相似文献   

11.
Ab initio total energy Hartree-Fock calculations of ultrathin films of α-Al2O3 on (0 0 0 1) α-Cr2O3 templates are presented. The surface relaxation, the in-plane reconstruction and the surface and strain energies of the slabs are studied as a function of alumina film thickness. The surface Al layer is found to relax inwards considerably, with the magnitude of the inwards relaxation depending on the thickness of the ultrathin alumina film in a non-linear manner. The calculations also reveal that ultrathin films of alumina lower the surface energy of (0 0 0 1) α-chromia substrates. This indicates that the (0 0 0 1) α-chromia surface provides favourable conditions for the templated growth of α-alumina. However, increasing the alumina film thickness is found to give rise to a significant increase in strain energy. Finally, the electronic properties at the surface of the (0 0 0 1) α-Al2O3/α-Cr2O3 slabs are investigated. Here it is found that the alumina coating gives rise to an increase in the covalency of the bonds at the surface of the slabs. In contrast, the influence of an alumina layer on the electrostatic potential at the surface of the chromia slab is relatively minor, which should also be beneficial for the templated growth of α-alumina on (0 0 0 1) α-chromia substrates.  相似文献   

12.
The shape and energy of the Ni K α1 X-ray emission line is shown to depend end on the composition of CuNi alloys across the entire alloy diagram. The magnetic transformation is clearly indicated in the width and position of Ni K α1 and the position of Cu K α1.  相似文献   

13.
In the work, we studied the evolution of structural and mechanical properties of 25Cr15Co hard magnetic alloy under shear deformation in Bridgman anvils at different rotation angles. It is shown that at the initial stage, severe plastic strains in a highly coercive (α1 + α2) state are localized in shear bands, in which the α1 and α2 phases are dissolved and an oversaturated a solid solution is formed. As this takes place, there arises a mixed structure consisting of misoriented fragments of the (α1 + α2) phase surrounded by interlayers of the a solid solution. A further increase in strain degree results in a single-phase nanocrystalline structure with a grain size of about 50 nm. It is found that the dissolution of the α1 phases in the α2 matrix under severe plastic deformation causes an increase in the strength characteristics and plasticity of 25Cr15Co alloy at all strain degrees under study. Maximum plasticity is found in the alloy with a mixed structure consisting of submicrocrystalline and cellular sites, and formation of nanocrystalline grains causes the plasticity to decrease somewhat.  相似文献   

14.
《Composite Interfaces》2013,20(6):521-541
In this study, nano α-alumina particles were synthesized by a sol–gel method using aqueous solutions of aluminum isopropoxide and 0.5?M aluminum nitrate. 1/3-benzene disoulfonic acid disodium salt (SDBS) and fluoride were used as surfactant stabilizing agent and additive, respectively. Results indicated that the finest size for nonagglomerated nanoalumina particles (15–20?nm) was achieved at 950?°C. The next part was about preparing PP nanocomposite containing nano α-Al2O3 particles. Mechanical tests, such as tensile, flexural, and impact tests showed that mechanical properties of the composite were enhanced by addition of nano α-Al2O3 particles and dispersant to the polymer. However, higher concentration of nano α-Al2O3 loading resulted in reduction of those mechanical properties, which could be due to agglomeration of nano α-Al2O3 particles. Transmission and scanning electron microscopic observations of the nanocomposites also showed that fracture surface became more roughened by increasing the content of filler loading from 1 to 4% wt.  相似文献   

15.
This paper represented the effect of welding wires on microstructure and mechanical properties of 2A12 aluminum alloy in CO2 laser-metal inter gas (MIG) hybrid welding. Plates of 2A12 aluminum alloy were welded by ER4043 and ER2319 welding wires, respectively. Full penetration joints without any defects were produced. The X-ray diffraction was used to analyze the phase composition, while the scanning electron microscopy (SEM) was conducted to study the microstructure, segregation behaviors of major alloying elements and the eutectics formed at dendrite boundaries in the joints. The results showed that silicon and copper were concentrated at the dendrite boundaries and α-Al + Si + Al2Cu + Mg2Si eutectic was formed if the ER4043 welding wire was used. However, only copper was concentrated at the dendrite boundaries and α-Al + θ eutectic was formed by ER2319 welding wire. Finally, the tensile tests were performed and the fracture surfaces were analyzed. The results showed that the joint efficiency by ER2319 and ER4043 welding wires reached up to 78% and 69%, respectively. Coarse dimples and voids had been observed in the fractographs. The joints showed a transgranular type failure.  相似文献   

16.
J. B. Ok  I. J. Kim  S. Yi  W. T. Kim 《哲学杂志》2013,93(20):2359-2369
Composites consisting of icosahedral (i) phase and ductile α-Mg can be fabricated by controlling the alloy composition. With increasing Mg content, the primary solidification phase changed from the i phase to the α-Mg phase and single eutectic structure can be obtained at a composition of Mg72Zn23.5Y3.5. The i phase showed a variation in structural order from the well-ordered icosahedral phase to the 1/1 rhombohedra1 approximant with lattice constants a=27.2 Å and α = 63.43°. The structural change in the i phase can be explained by microdomain formation due to compositional change during solidification. Annealing treatment improves the structural order of the i phase by homogenization. By controlling the alloy composition, a single eutectic structure consisting of a hard i phase and a ductile α-Mg phase could be obtained.  相似文献   

17.
Nano-structured α-Fe1.4Ti0.6O3 has been synthesized using a simple technique of mechanical alloying. Doping of Ti atoms into α-Fe2O3 structure has been characterized by XRD, SEM-EDX, FTIR, VSM and impedance spectroscopy. Magnetic and electrical studies have revealed important changes at the interfaces of grains and grain boundaries, and at rhombohedral planes during formation of α-Fe1.4Ti0.6O3 alloy. The alloy has shown the properties of ferromagnetic semiconductor with substantial increase of magnetic moment and electrical conductivity with the decrease of grain size. The 100 h milled sample has been air annealed to study the effects of thermal activated grain size, lattice structure, magnetism and electrical properties. This work has demonstrated some recent issues of the synthesis of ferromagnetic semiconductor, e.g., structural phase stability, grain size effects, magnetic ordering and electrical conductivity at different stages of the mechanical alloying and subsequent annealing at 700 °C.  相似文献   

18.
Blends of poly(vinyl chloride) (PVC) and poly(α-methylstyrene-acrylonitrile) (α-MSAN) with variable composition of 0 to 100 wt% were prepared by melt mixing. Properties of binary blends were extensively studied by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), heat distortion temperature (HDT), mechanical properties, melt flow rate (MFR), and scanning electron microscope (SEM). A single glass transition temperature (Tg ) was observed by DSC and DMTA, indicating miscibility between PVC and α-MSAN. The results of ATR-FTIR indicated that specific strong interactions were not present in the blends and the miscibility was due to interaction between –CN and PVC. With increasing amount of α-MSAN, considerable increase occurred in HDT, flexural strength, and flexural modulus compared with reverse s-shaped decrease in impact strength and elongation at break. Synergism was observed in tensile strength and MFR. No phase separation was observed in SEM photographs, indicating miscibility between PVC and α-MSAN. In addition, morphology of the impact-fractured surfaces, including roughness and non-fused particles, correlated well with the mechanical properties and MFR.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号