去合金化工艺对纳米多孔铜纯度的影响

采用腐蚀去合金化方法制备纳米多孔铜材料。研究了固溶时间、腐蚀时间及腐蚀温度对纳米多孔铜表面形貌及残余Mn含量的影响。研究表明:由于固溶时间的延长，合金成分越来越均匀化，去合金化后所得纳米多孔铜的残余Mn原子分数降低。固溶95 h的前驱体合金，随着腐蚀时间的延长，其残余Mn含量降低不明显；随着温度的升高，其残余Mn原子分数由25 ℃的3.54%降至60℃的1.14%，但是60 ℃腐蚀后的孔隙与丝径尺寸明显粗化，样品易碎。通过调整去合金化参数，实验所制备的纳米多孔铜呈现均匀的海绵状纳米多孔结构，残余Mn原子分数1.23%, 平均丝径尺寸40 nm。     

去合金化制备纳米多孔铜

 以Mn-Cu合金为前驱体合金,在0.1 mol/L HCl 溶液中自由腐蚀去合金化成功制备出纳米多孔铜,采用扫描电镜和X射线能谱仪对去合金腐蚀前后样品的形貌和成分进行了分析,结果表明,Mn-Cu合金在0.1 mol/L HCl 溶液中发生锰的选择性溶解,制备出的纳米多孔铜呈3维网络状均匀结构,平均系带尺寸53 nm,平均孔径尺寸为140 nm。     

自支撑纳米多孔金薄膜制备研究

采用磁控溅射镀金银膜,长时间热处理合金化制备前驱体合金,以渐进浓度的硝酸自由腐蚀去合金化成功制备出具有自支撑结构的纳米多孔金薄膜。采用扫描电镜和X射线能谱仪对去合金腐蚀前后样品的形貌和成分进行了分析,结果表明:400℃,36h的热处理使得薄膜样品完全合金化,获得了结晶致密的Au42Ag58合金膜;渐进浓度的自由腐蚀避免了薄膜的完全开裂,获得了样品尺寸大于15mm×15mm、厚度400~500nm、孔隙率约56%、具有自支撑结构的纳米多孔金薄膜,其微观结构为连续的三维多孔结构,系带尺寸40~140nm,80~100nm的系带达58%。     

激光熔覆铜锰合金选择性脱合金制备纳米多孔涂层的研究

本文通过激光加工结合电化学腐蚀脱合金法, 成功实现了纳米多孔涂层的制备. 采用激光熔覆首先在45钢表面制备了成形良好、稀释率低的铜锰合金熔覆层, 并通过快速重熔工艺实现了初始材料组织细化. 研究表明, 在不同的电解液下,铜锰合金的临界腐蚀电位出现了明显的偏移; 在不同的腐蚀电流下,铜锰合金腐蚀后的形貌迥异. 最终,通过选择性腐蚀成功实现了纳米多孔铜和纳米多孔锰涂层的制备, 并利用电位-pH图对脱合金的选择性腐蚀进行了详细的理论解释.     

银铜双原子MACE法可控制备倒金字塔多晶黑硅的结构与性能

采用一步银铜双原子金属辅助化学腐蚀法,室温下在多晶硅表面制备纳米陷光结构,再利用纳米结构修正溶液在温度为50℃时对硅片进行各向异性重构,可控制备出不同尺寸的倒金字塔陷光结构.用分光光度计测量了多晶硅表面的反射率,用扫描电镜观察了多晶硅表面形貌,用少子寿命测试仪测量了多晶硅钝化后的少子寿命.结果表明:影响倒金字塔结构尺寸的主要影响因素是制备态黑硅纳米结构的深度,当深度越深,最终形成的结构尺寸也越大;纳米结构修正溶液重构时间越长,所形成的倒金字塔结构尺寸越大,反射率也变大;经原子层沉积钝化后的倒金字塔结构中少子寿命随其尺寸的增大而增加;当倒金字塔边长为600nm时综合效果最佳,反射率为9.87%,少子寿命为37.82μs.     

机械合金化Fe100-xCux体系的X射线吸收精细结构研究

利用X射线吸收精细结构(XAFS)方法研究机械合金化制备的Fe_100-xCu_x(x=0,10,20,40,60,70,80,100,x为原子百分比)合金中Fe和Cu原子的局域环境结构.对于Fe_100-xCu_x(x≥40)二元混合物,球磨160h后,Fe原子的近邻配位结构从bcc转变为fcc,但Cu原子的近邻结构保持其fcc不变.与之相反,在Fe₈₀Cu₂₀和Fe₉₀Cu₁₀(x≤20)合金中,Fe原子的近邻配位保持其bcc结构而Cu原子的近邻配位结构从fcc转变为bcc结构.XAFS结果还表明,fcc结构的Fe_100-xCu_x样品中Fe的无序因子σ(0.0099nm)比bcc结构的Fe_100-xCu_x中的σ(0.0081nm)大得多;并且在机械合金化Fe_100-xCu_x(x≥40)样品中Fe原子的σ(0.0099nm)比其Cu原子的σ(0.0089nm)大.这表明机械合金化Fe_100-xCu_x样品中Fe和Cu原子可以有相同的局域结构环境但不是均匀的过饱和固溶体,而是由Fe富集区和Cu富集区组成的合金.我们提出互扩散和诱导相变机理来解释在球磨过程中Fe_100-xCu_x合金产生从bcc到fcc和从fcc到bcc变化的结构相变 关键词： XAFS 100-xCu_x合金')" href="#">Fe_100-xCu_x合金 机械合金化     

相场法研究Fe-Cu-Mn-Al合金富Cu相析出机制

基于Ginzburg-Landau理论采用连续相场法模拟了Fe-15%Cu-3%Mn-x Al(质量分数x=1%, 3%, 5%)合金在873 K等温时效时纳米富Cu析出相沉淀机制及Al含量对富Cu相析出的阻碍效应.通过计算成分场变量和结构序参数,研究了富Cu析出相的形貌、颗粒密度、平均颗粒半径、生长和粗化动力学.研究结果表明:在时效早期阶段,纳米富Cu相通过失稳分解机制析出,由于原子扩散速率存在差异,从而形成以富Cu相为核心的核壳结构.随着时效时间延长,富Cu相析出物结构由体心立方转变为面心立方.其中Al和Mn原子在富Cu核外偏析形成Al/Mn簇,可以将其视为阻碍富Cu析出相形成的缓冲层;在沉淀过程中,随着Al含量的增大, Al/Mn金属间相促进了缓冲层的生长,阻碍富Cu析出相的生长和粗化.     

退火诱导亚稳态Fe80Cu20合金固溶体的结构相变

利用扩展x射线吸收精细结构和x射线衍射研究了机械合金化制备的体心立方(bcc)的亚稳态Fe80Cu20合金固溶体的结构随退火温度的变化特点.结果表明,在300-873 K温度范围内,随着退火温度的升高,bcc结构物相的晶格常数近于线性降低,这主要是由于Cu原子从bcc结构Fe80Cu20合金固溶体中逐渐偏析出来,生成面心立方(fcc)结构的Cu物相所致.经603 K退火后,Cu原子的平均键长RCu-Cu增加了0.003 nm左右,大约有50%的Cu原子从bcc结构的Fe80Cu20合金固溶体中偏析出来.在773 K退火后,bcc结构Fe80Cu20合金固溶体近于完全相分离,生成了bcc结构的α-Fe与fcc结构的Cu物相.     

单辊旋淬法制纳米晶铜铍合金及结构分析

 采用单辊旋淬法制备出纳米晶CuBe合金,利用X射线衍射、扫描电镜以及电子能谱等分析方法对纳米晶铜铍合金进行结构分析,并与原始态的CuBe合金的相结构进行了对比。研究表明：合理的快速凝固工艺能使铜铍合金的晶粒尺寸达到30 nm左右,晶粒形貌发生变化,并且有类似CuBe的金属间化合物出现。由于铍原子加入到纯铜中,使得铜铍合金的固溶度扩大,在快速凝固铜合金中有大量细小弥散的第二相颗粒,有共析转变发生。     

XAFS和XRD研究高能球磨对Fe70Cu30合金结构的影响

利用XRD和XAFS方法研究机械合金化Fe70Cu30二元金属合金随球磨时间的结构变化.XRD结果表明,球磨2 h后,部分金属Fe与Cu生成Fe-Cu合金;球磨20h后,金属Fe与Cu已完全合金化生成Fe-Cu合金,并只在2θ=44°处出现一个宽化的弱衍射峰,认为是在球磨20h后的Fe70Cu30合金中共存着fcc和bcc结构的Fe-Cu合金相.XAFS结果进一步表明,在球磨的初始阶段(2h),fcc结构的Cu颗粒的晶格产生较大的畸变,其无序度σ(σ＝σT+σS)为0.0190nm.球磨5h后,部分fcc结构的Cu原子进入了无序度相对较小的bcc结构的α-Fe相,导致Cu原子的平均无序度σ降为0.0108 nm.球磨10h后,样品中很大比例的Fe原子处于fcc结构的Fe-Cu合金相,其无序度为σ=0.0119 nm;而大部分Cu原子依然保持fcc结构,无序度为σ=0.0110 nm.这是由于扩散到bcc结构α-Fe相的Cu原子超过某一浓度后(约30%-40%),Cu原子能诱导其产生fcc结构相变所致.球磨时间增加到20h,样品中Cu原子和Fe原子在fcc和bcc相的比例与球磨10h基本相同,生成的Fe-Cu合金混合相的组成和结构分别近似于bcc结构的Fe80Cu20和fcc结构的Fe60Cu40.     

Mn-Cu系高阻尼合金的凝固组织控制及阻尼特性的改善

Mn—Cu系阻尼合金兼有较高的阻尼特性和良好的力学性质，因而具有较大的实用前景。这类合金通常经过铸造，塑性加工和热处理来获得要求的性能和组织。加工后的Mn—Cu合金存在一个特定温度，在此温度以上合金的阻尼性能将会消失，因而影响了合金的在较高温度下的使用。该温度和合金的Mn含量有关，然而提高合金的Mn含量有会降低合金的加工性及力学性能。一般Mn-Cu合金的热处理都是利用400℃附近的时效来获得相分解后的局部高Mn组织。但是目前的时效处理后的Mn—Cu阻尼合金的最高使用温度只在80℃以下。为解决Mn—Cu阻尼合金使用温度的局限性，本研究选用凝固过程控制的方法在铸造组织中来获得较大幅度的Mn含量分布。从而在Mn-Cu合金得到较高的高阻尼特性温度。本工作利用铸型温度控制的方法，将M2052（Mn-20Cu-5Ni-2Fe）合金在250～0．1K／s冷却速度范围内控制凝固。随凝固冷却速度的降低在合金的铸态组织中观察到二次枝晶间距和晶粒尺寸的明显增大。同时还发现缓冷凝固的合金的成分比快冷凝固有较大的分布幅度。铸态下的合金阻尼性能评价也证实了凝固冷却速度对合金的凝固组织有很大的影响。尽管铸态组织的合金的高温阻尼性能并没有很大的改善，然而通过对铸态组织实施时效处理后发现缓冷凝固合金的高温阻尼性能有很大的改善。凝固冷却速度对时效处理后合金的阻尼性能有明显的影响。实验结果表明0．1K／s的冷却速度下缓慢凝固的合金在时效处理后高阻尼特性可持续高达120℃．     

Room temperature precipitation in quenched Al–Cu–Mg alloys: a model for the reaction kinetics and yield strength development

The microstructural evolution during low temperature ageing of two commercial purity alloys (Al–1.2Cu–1.2Mg–0.2Mn and Al–1.9Cu–1.6Mg–0.2Mn?at.%) was investigated. The initial stage of hardening in these alloys is very rapid, with the alloys nearly doubling in hardness during 20?h ageing at room temperature. The microstructural evolution during this stage of hardening was investigated using differential scanning calorimetry (DSC), isothermal calorimetry and three–dimensional atom probe analysis (3DAP). It is found that, during the hardening, a substantial exothermic heat evolution occurs and that the only microstructural change involves the formation of Cu–Mg co–clusters. The kinetics of cluster formation is analysed and the magnitude of the hardening is discussed on the basis of a model incorporating solid solution hardening and modulus hardening originating from the difference in modulus between Al and clusters.     

Magnetic structure of single-domain antiferromagnetic FCT γ-Mn-Cu and γ-Mn-Fe alloys

Detailed neutron diffraction studies both by double axis and triple axis spectrometer are reported for the first time for fct single-domain single crystals of γ-Mn-Cu and γ-Mn-Fe. The main purpose of these studies was to elucidate further the nature of the diffuse (001) peak, forbidden by the AF1 magnetic structure, established earlier in this group of γ-Mn alloys. Line shapes and their temperature dependence were measured for (001), (100) and (010) reflections in Mn-Fe and in Mn—Cu, in the latter case both for homogeneous (quenched) and chemically decomposed (aged) samples. Only (001) reflection was found in Mn-Fe, while in Mn-Cu samples diffuse peaks were also observed at (100) and (010). Together with their temperature dependence and the results of energy analysis the data suggest a new model of the magnetic structure of these alloys. In Mn-Fe the spins deviate by a fixed angle from the c axis and this perturbation has an infinite correlation range and life time. In Mn-Cu a more complex set of perturbations is required to interpret the data.     

The neutron structural analysis in studies of diffusionless phase transitions in shape memory alloys

The characteristics of alloys with the shape memory effect are presented. The physical nature of the process of a change in the shape is examined. The structure of the high-manganese alloys of Mn-Cu system with shape memory is described. The role of neutron analysis in studies of structural transformations in Mn-Cu alloys is shown. On the basis of the results of measuring the temperature dependences of internal friction in the magnetic fields of different magnetizing force, the presence of the magnetic contribution to the pretransition anomalies in Mn-Cu alloys is assumed. The prospects of applying the neutron analysis in studies of alloys with the shape memory generally and, in particularly, in the Mn-Cu alloys are shown.     

KKR-CPA-LDA计算方法对CuMnAl和CoMnAl以及CuCoMnAl合金的磁性研究

采用KKR-CPA-LDA方法研究了CuMnAl,CoMnAl和CuCoMnAl四元合金中磁性原子磁矩和Co-Mn间的交换作用.通过与实验结果对比,揭示了Mn的磁矩和Co的磁矩以及它们的相互作用随成分变化的规律.研究发现,在Cu₅₀Mn_25+xAl25-x合金中超过化学配比并占据Al位的Mn原子是反铁磁的,而且由于近邻环境的不同,其磁矩大于原有Mn原子的磁矩.在Co₅₀Mn_{25+< 关键词： KKR-CPA-LDA计算 Co-Mn间交换作用}     

Microstructural evolution in Al–Mn–Cu–(Be) alloys

This study investigates the effects of alloying elements on the microstructural evolution of Al-rich Al–Mn–Cu–(Be) alloys during solidification, and subsequent heating and annealing. The samples were characterised using scanning electron microscopy, energy dispersive X-ray spectroscopy, synchrotron X-ray diffraction, time-of-flight secondary-ion mass spectroscopy, and differential scanning calorimetry. In the ternary Al₉₄Mn₃Cu₃ (at%) alloy, the phases formed during slower cooling (≈1?K?s^?1) can be predicted by the known Al–Mn–Cu phase diagram. The addition of Be prevented the formation of Al₆Mn, decreased the fraction of τ₁-Al₂₉Mn₆Cu₄, and increased the fraction of Al₄Mn. During faster cooling (≈1000?K?s^?1), Al₄Mn predominantly formed in the ternary alloy, whereas, in the quaternary alloys, the icosahedral quasicrystalline phase dominated. Further heating and annealing of the alloys caused an increase in the volume fractions of τ₁ in all alloys and Be₄Al (Mn,Cu) in quaternary alloys, while fractions of all other intermetallic phases decreased. Solidification with a moderate cooling rate (≈1000?K?s^?1) caused considerable strengthening, which was reduced by annealing for up to 25% in the quaternary alloys, while hardness remained almost the same in the ternary alloy.     

Magnetic susceptibility and electrical resistivity of dilute liquid copper - iron alloys

Electrical resistivity and magnetic susceptibility measurements on dilute liquid CuFe alloys are reported. Small additions of Fe increase the resistivity of liquid Cu in a drastic manner, whereas the temperature coefficient is found to be decreased. Due to the localized magnetic moments of the impurity atoms the diamagnetism of Cu is converted into a strong temperature-dependent paramagnetism indicating about 3.5 unpaired d electrons per Fe atom. The electronic properties of CuFe resemble those of liquid CuMn and AuFe which, in the solid state, are known for their Kondo-like behaviour. The experimental findings are tentatively interpreted in terms of spin-disorder scattering with special emphasis on the negative temperature coefficient of the impurity resistivity.     

Heusler合金Mn2NiGe磁性形状记忆效应的第一性原理预测

运用基于密度泛函理论的第一性原理,对Hg₂CuTi型Mn₂NiGe的四方变形、晶体结构、磁性、电子结构、压力响应等进行了计算.计算结果表明: 1)在由立方结构至四方结构的转变中,在c/a约为1.34处存在一个稳定的马氏体相;2)在奥氏体态和马氏体态下,Mn原子均是Mn₂NiGe总磁矩的主要贡献者,但Mn(A),Mn(B)原子磁矩的值不等且呈反平行耦合,因而Mn₂N 关键词： 第一性原理 磁性形状记忆 四方变形 马氏体相变     

The effect of quaternary element on the thermodynamic parameters and structure of CuAlMn shape memory alloys

In this study, the Cu-based shape memory alloys were produced by arc melting. We have investigated the effects of the alloying elements on the characteristic transformation temperatures, enthalpy, entropy values, and the structure of Cu–Al–Mn ternary system. The evolution of the transformation temperatures was studied by the differential scanning calorimetry. The characteristic transformation temperatures can be controlled by the variations in the aluminum and manganese content. Additionally, the effect of magnesium and iron on the transformation temperatures and thermodynamic parameters was investigated in the Cu–Al–Mn ternary system. The addition of the magnesium decreases the characteristic transformation temperatures of the Cu–Al–Mn system, but that of the iron increases. The structural changes of the samples were studied by X-ray diffraction measurements and optical microscope observations. Due to the low solubility of the magnesium, the magnesium addition into the Cu–Al–Mn system forms precipitates in the matrix. It is evaluated that the transformation parameters of the CuAlMn shape memory alloys can be controlled by the change of the alloying elements and the weight percentages of alloying elements.