常温常压下 Cu-Zn-Al合金一维纳米结构的制备

常温常压下,以Cu-Zn-Al合金为基体,经过适当的混和酸处理,制得了几种形貌和结构不同的一维合金纳米结构.通过能量弥散X射线(EDX)分析表明它们的主要成分是Cu、Zn、Al,其直径一般在20～50nm左右,最长长度达1600nm.合金中存在的非线性振荡,以及酸处理后产生纳米粒子是生成一维合金纳米机构的关键.结合透射电子显微镜照片初步分析了一维合金纳米结构的生长机制并给出了生长模型.     

一维Cu-Zn-Al合金纳米结构的制备及生长机理研究

Cu-Zn-Al合金经过简单的混合酸处理后,成功地在常温常压下制备出两种形态、组成不同的纳米管.能量衍射谱表明其主要成分是Cu,Zn,Al和Si,Al,O.其管径一般在20～50nm左右,最长长度达1600nm.研究发现,在混和酸处理后产生的分散程度很高的纳米粒子在纳米管的生长中起了重要作用,结合生长模型和透射电子显微镜照片初步分析了这种作用的机理和合金纳米管的生长机理.     

Cu-Zn-Al系合金的马氏体稳定化

本文以电阻法和圆弧压弯法研究了ＣｕＺｎＡｌ系合金热弹性马氏体的稳定化过程，用ＤＴＡ法测定了母相Ｂ２→ＤＯ３有序转变温度，分析了合金元素Ｍｎ对ＣｕＺｎＡｌ系合金马氏体稳定化的影响，实验结果表明：热弹性马氏体的稳定化倾向与Ｂ２→ＤＯ３转变温度的高低有关。由此解释了Ｍｎ对改善ＣｕＺｎＡｌ系合金马氏体稳定化的作用。     

机械合金化制备纳米Cu-Zn-Al2O3复合粉末的研究

采用X射线衍射仪、电子扫描电镜和透射电镜等研究了Ar气氛保护下Cu-Zn-Al2O3复合粉末在高能球磨过程中发生的机械合金化反应,分析了不同球磨时间对a-Cu(Zn)的晶格常数、晶粒尺寸以及复合粉末粉体形貌、颗粒尺寸的影响.结果表明,球磨初期,Cu的晶格常数增大,但75h后由于γ相的析出,a-Cu(Zn)晶格常数减小;高能球磨120h后,可获得氧化铝颗粒弥散分布的纳米级Cu(Zn)复合粉末.     

管状纳米结构的合成及显微分析

自从１９９１年ＮＥＣ的Ｉｉｊｉｍａ研究员发现碳纳米管以来,管状纳米结构引起了世界范围内的物理、化学、材料等学界的广泛重视。描述了用激光蒸发法在高温氮气气氛中合成单层碳纳米管,Ｂ－Ｃ－Ｎ复合纳米管,ＢＣＮ／ＳｉＯ２／ＳｉＣ多层纳米电缆结构的工作,以及运用高分辨电子显微镜和纳米区域电子能量损失谱仪对其结构和化学组成进行分析的结果,并讨论了激光蒸发法中管状纳米结构的生成机理。     

纳米晶Ag—Cu合金的结构

用Ｘ－射线衍射，维氏显微硬度测量等方法研究了在惰性气体中蒸发Ａｇ－Ｃｕ母合金，然后原位加压成型得到的纳米晶Ａｇ－Ｃｕ合金，实验结果表明，ｎ－Ａｇ３７Ｃｕ６３合金由富根，富铜固溶体组成，点阵参数随退火温度的变化表明，它们是快速冷却超粒子时产生的孢和固溶全，样品的维氏显显镀昌粒的长大而减小，遵循Ｈａｌｌ－Ｐｅｔｃｈ关系。     

纳米针状In(OH)3中残留氯元素的存在状态研究

采用高分辨透射电子显微术(HRTEM)分析纳米针状In(OH)3粉末中氯元素的存在状态.分析结果显示,氯元素主要以In5Cl9的形式存在,并且未探测到其他种类的InxCly化合物.In5Cl9中最容易观察到的晶面为(110)面(d=0.617 nm)和(113)面(d=0.428 nm).     

分叉纳米碳管与直纳米碳管拉伸力学特性的分子动力学研究

采用分子动力学方法,模拟了分叉纳米碳管与直纳米碳管的拉伸过程,对比、分析了分叉纳米碳管与直纳米碳管的拉伸力学性能。研究表明,分叉纳米碳管拉伸时的屈服与断裂发生在其粗管与细管过渡处,其抗拉强度与韧性分别低于直纳米碳管24％和17％,然而,其弹性模量却与直纳米碳管相当。     

纳米储氢合金制备方法的研究进展

纳米储氢合金的热力学与动力学性能明显超过了相应的微米级合金 ,引起了储氢合金研究者的关注 ,而目前纳米储氢合金的制备方法仅集中于球磨法。本文总结了纳米储氢合金颗粒与复合材料的制备方法 ;并从纳米材料制备技术的角度 ,对潜在的纳米储氢合金的制备方法进行了评述     

不同合金元素对FINEMET合金的性能和纳米结构的影响的研究进展

随着世界范围内对高性能软磁材料的需求日益增加,添加不同合金元素的FINEMET合金的性能及其纳米结构的研究近年来引起了广大科研工作者的兴趣.本文回顾了不同合金元素对软磁合金材料的纳米结构和性能的影响的研究进展,并讨论了不同热处理工艺对合金软磁性能的影响.要更进一步的降低成本和提高材料性能,我们必须对合金成分,合金制备方法及热处理工艺进行优化.     

Thermoelastic martensitic transformation in Cu-Zn-Al alloy

Thermoelastic martensitic transformation in a Cu-29% Zn-3% Al alloy has been observed with optical and electron microscopy, including 1.0–1.2 MV high-voltage transmission electron microscopy (TEM), and treated with the phenomenological theory suggested before. The observation showed that the transformation was conducted in three stages: parallel plates growing, self-accommodating variants advancing, and plates merging and/or tiny plates forming in carved-up parent phase areas. TEM showed that the martensite consisted of a huge number of packets with constant size and distinct interfaces. By using the phenomenological theory, the free-energy function as well as the friction quasi-enthalpy and friction quasi-entropy are obtained in SI units. Comparing with classical theory, the free energy can be broken into three parts: the chemical free energy, the interfacial energy and the elastic strain energy. In the range of 20–70% martensite in the alloy, the interfacial energy per unit of martensite formation is constant and the corresponding elastic strain energy is a linear function of martensite percentage. Some possible explanations for this energetics relating to the observation are given.     

电沉积铁镍纳米合金薄膜的结构和性能研究

采用电沉积方法从硫酸盐体系镀液中沉积得到Fe18Ni82合金薄膜.运用扫描电子显微镜(SEM),原子力显微镜(AFM),透射电子显微镜(TEM)和X射线衍射分析(XRD)以及磁测量设备分别对薄膜的表面形貌、显微结构和磁性能进行表征和测量.同时利用万能材料试验机和显微硬度计测量了薄膜的力学性能.结果表明:电沉积制备的Fe18Ni82合金薄膜成分均匀,表面平整、光亮、致密,晶粒大小为40～50 nm.薄膜是以Ni为溶剂原子,Fe为溶质原子的置换型固溶体,只存在单一的fcc相,Fei8Ni82合金薄膜沿(111)面有较强的择优取向.镀态Fei8Ni82合金薄膜在50 Hz交流磁场下,测得其饱和磁感应强度为1.08 T,最低矫顽力为20 A/m.19 μm厚的纳米晶薄膜的断裂应力达到785MPa,显微硬度达到605Hv.     

TEM study of the decomposition of the Heusler alloy Cu2MnAl

Investigation of the equilibrium phase precipitation in the alloy Cu_2.00Mn_1.00 Al_1.00 performed previously by X-ray diffraction, magnesometry, SEM and resistometry was continued by means of TEM. It was found that the and-Mn precipitation mechanism was cellular in most cases. No T-phase precipitates were detected. The new results were compared with the previous ones and the temperature dependence of the-phase decomposition mechanism was explained in terms of the classical phase diagram of the Cu-Mn-Al system.     

TEM observatiion of a Cu-Mg age-hardenable alloy

The precipitation processes in Cu-Be, Cu-Co, Cu-Fe alloys have been thoroughly investigated; however, much less attention has been paid to studying the Cu-Mg system. In this work the decomposition of Cu-3.5 wt% Mg alloy during ageing was investigated by means of transmission electron microscopy (TEM). The microstructure of Cu-3.5 wt% Mg alloy aged at 340° C is characterized by the presence of fine dispersed coherent precipitates. On continued ageing the coherent precipitates disappear and a new transition phase with oblate octahedron morphology grows. At temperatures above 34O° C the equilibrium phase is formed by discontinuous precipitation. Ageing of Cu-3.5 wt% Mg alloy at temperatures above 450° C results in the formation of the equilibrium Cu₂Mg phase.     

TEM study of microstructure development during low-cycle fatigue of an overaged Al-Mg-Si alloy

The evolution of dislocation structure during room-temperature, uniaxial, low-cycle fatigue of an overaged Al-Mg-Si alloy is studied. Ageing at 450°C produces a fine dispersion of Mg₂Si precipitate particles. During fully reversed strain-controlled cyclic tests, these fine particles restrict deformation to local regions and a stable dislocation substructure is developed early in fatigue life. Substructural observations of hardening and saturation by transmission electron microscopy reveal extensive dislocation band formation on Mg₂Si precipitate rods. Various microstructural features such as configuration of tangled dislocations, dislocation cells, precipitate morphologies, sizes, precipitate-free zones, etc., have been examined during cyclic hardening and saturation. The results have been analysed in terms of kinematic and isotropictype microstructural mechanisms.     

钛酸纳米管的制备及 TEM表征

采用水热合成法以金红石型纳米TiO2粉为原料制备钛酸纳米管，考察了搅拌、酸洗及焙烧温度对纳米管的形成和结构的影响，并通过TEM观察了产物的形貌、结构．结果显示：持续搅拌能促进原料粉末的定向生长，有利于形成钛酸纳米片；酸洗是纳米管的形成阶段；300℃是纳米管转变为长棒状晶柱的临界温度．实验表明以优化的水热合成法制得的纳米管形貌均一，长度超过1μm，钛酸纳米管长径比为125：1．     

Effect of cooling rate on the order in martensite of a Cu-Zn-Al alloy

The martensite structure and order state of Cu-18Zn-14Al alloy was studied by means of X-ray diffraction. The alloy was subjected to four different quenching treatments. As the quenching rate decreased, the nnn order degree of the alloy increased and the nn order degree remained almost unchanged. The splitting parameter = |sin²₁ – sin² ₂| and the monoclinic angle changed very little. In addition, the order state of the alloy was calculated according to its crystal structure model. It is suggested that only the Zn and Al atoms exchange along the b-axis as the nnn order decreases, which slightly influences crystal symmetry and lattice constant.