Ni/NiO界面的高场磁化研究

报道在表面包覆ＮｉＯ的Ｎｉ超微颗粒和Ｎｉ／ＮｉＯ多层膜中Ｎｉ／ＮｉＯ界面的磁性实验结果．在Ｔ＜８０Ｋ下Ｎｉ／ＮｉＯ界面存在较大的磁化强度（Ｈ＝４０kＯｅ），并随温度上升而快速下降．对高场磁化（５－６５kＯｅ）实验数据进行拟合，结果表明Ｎｉ／ＮｉＯ界面存在类似磁矩排列不一致的结构． 关键词：     

Ni/W金属超晶格中的反常阻温特性

在室温到１５Ｋ范围内我们对Ｎｉ／Ｗ金属超晶格的输运性质进行了测量。随温度的降低，反常的电阻跳跃被发现，这种现象被归因子Ｎｉ／Ｗ超晶格样品从晶态到非晶态的结构相变。温度降低时，样品界面处的原子无序度增大，当这种无序积累到一定程度时样品发生从晶态到非晶态的结构相变。     

88Ni—Fe合金超细微料的制备,磁性以及热分析

气相蒸发法制备的８δａｔ％Ｎｉ－Ｆｅ合金超细微粒，平均粒径为５￣８４ｎｍ。观察、分析了样品的形貌、结构、成分、磁性、表面吸附以及氧化等。结果表明，微粒晶体结构呈面心立方，晶格常数及成分均接近于块材，表面吸附一层氮气分子。微粒单畴临界尺寸约为３７ｎｍ，由此算出有效各向异性常数为６．１６×１０＾５ｅｒｔ·ｃｍ＾－３，远大于块材。发现样品的居里温度呈现一定分布，并与微粒的尺寸分布及其表面（界面）层有关。     

Ni／Zr双层膜中固态非晶化的分子动力学模拟

文章采用多体势，用分子动力学模拟研究了含有无序界面的Ｎｉ／Ｚｒ双层膜在等温退火下的自发非晶化过程．在原子尺度上首次观察到了Ｎｉ－Ｚｒ之间的互扩散和合金化，以及由此导致的从界面开始、由扩散控制的非晶化．     

镍基单晶超合金Ni/Ni3Al晶界的分子动力学模拟

在镍基单晶超合金中,由于单晶Ni的晶格常数比单晶Ni3Al的稍小,在Ni/Ni3Al晶界面上必然要出现错配.采用分子动力学模拟了镍基单晶超合金的Ni/Ni3Al晶界的结构,考虑了两个不同的初始模型,并进行了分子动力学弛豫.弛豫的结果均表明:由于晶格的差异形成的错配能不是通过长程晶格错配的方式来释放,而是通过在局部区域形成位错的方式释放的.由于Ni3Al相周围Ni相环境的不同,形成的位错也有所不同.     

镍基单晶超合金Ni/Ni3Al晶界的分子动力学模拟

在镍基单晶超合金中，由于单晶Ni的晶格常数比单晶Ni₃Al的稍小，在Ni/Ni3Al晶界面 上必然要出现错配.采用分子动力学模拟了镍基单晶超合金的Ni/Ni₃Al晶界的结 构，考虑 了两个不同的初始模型，并进行了分子动力学弛豫.弛豫的结果均表明：由于晶格的差异形 成的错配能不是通过长程晶格错配的方式来释放，而是通过在局部区域形成位错的方式释放 的.由于Ni₃Al相周围Ni相环境的不同，形成的位错也有所不同. 关键词： 镍基单晶超合金 晶界 分子动力学模拟     

用IRIS/AP-ICP-AES法同时测定废水中的Cd、Cr、Cu、Ni、Pb和Zn

本文采用ＩＲＩＳ／ＡＰ－ＩＣＰ－ＡＥＳ法同时测定废水中的Ｃｄ、Ｃｒ、Ｃｕ、Ｎｉ、Ｐｂ和Ｚｎ,选择了最佳的仪器工作条件,并选取了被测元素的最佳谱线,样品中的干扰因子通过谱线的背景校正方法予以消除,本法操作简便,结果准确,其相对标准偏差均小于２％,回收率在９８％－１０４％之间。     

Ni（II）与壳聚糖的配位作用及其催化性质的研究

用ＥＳＲ、ＸＰＳ、ＩＲ、ＵＶ－Ｖｉｓ、ＤＴＡ－ＴＧ和电导率法研究Ｎｉ（Ⅱ）与壳聚糖（ＣＳ）的配位作用、所形成的配位聚合物（配聚物）的组成和结构。确定Ｎｉ（Ⅱ）与ＣＳ分子以配位键相结合形成高自旋Ｎｉ－ＣＳ配聚物，配聚物的配位单元由１个Ｎｉ（Ⅱ）与３个ＣＳ单体单元的氨基Ｎ原子和仲羟基Ｏ原子形成扭曲的六配位的八面体结构所组成。此外，对Ｎｉ－ＣＳ配聚物与Ｎａ２ＳＯ３体系在ＭＭＡ聚合中的催化性质进行了研究。     

石墨炉原子吸收光谱法测定血清中的微量Mn,Ni,Co和Cr

本文建立了一种用石墨炉原子吸收光谱法测定血清中微量Ｍｎ，Ｎｉ，Ｃｏ和Ｃｒ的方法，血清以０．２％硝酸和ｔｒｉｔｏｎ Ｘ－１００混合溶液稀释１０倍后直接测定，方法简便，快速，回收率为９０－１１０￥，相对标准偏差为３．２６－４．３８％。     

EXAFS研究负载型Ni／SiO2的区域结构

实验结果表明改进的实验室ＥＸＡＦＳ谱仪测试Ｎｉ箔的Ｋ吸收得到的ＥＸＡＦＳ谱与同步辐射上测量Ｎｉ箔得到的ＥＸＡＦＳ谱相近，利用实验室ＥＸＡＦＳ方法也可开展较好的结果测量研究，在ＳｉＯ２粉末载体上Ｎｉ负载量变化的ＥＸＡＦＳ结果表明，随着Ｎｉ负载量的降低，Ｎｉ的径向结构函数主配位峰的位置Ｒ＝０．２２０ｎｍ保持不变，但振幅强度逐渐降低。负载量从Ｎｉ箔到２．５％Ｎｉ／ＳｉＯ２，无序度因子σ由０．００６８ｎｍ     

Molecular dynamics study of plastic deformation mechanism in Cu/Ag multilayers

The plastic deformation mechanism of Cu/Ag multilayers is investigated by molecular dynamics(MD) simulation in a nanoindentation process. The result shows that due to the interface barrier, the dislocations pile-up at the interface and then the plastic deformation of the Ag matrix occurs due to the nucleation and emission of dislocations from the interface and the dislocation propagation through the interface. In addition, it is found that the incipient plastic deformation of Cu/Ag multilayers is postponed, compared with that of bulk single-crystal Cu. The plastic deformation of Cu/Ag multilayers is affected by the lattice mismatch more than by the difference in stacking fault energy(SFE) between Cu and Ag. The dislocation pile-up at the interface is determined by the obstruction of the mismatch dislocation network and the attraction of the image force. Furthermore, this work provides a basis for further understanding and tailoring metal multilayers with good mechanical properties, which may facilitate the design and development of multilayer materials with low cost production strategies.     

界面结构对Cu/Ni多层膜纳米压痕特性影响的分子动力学模拟

金属多层膜调制周期下降到纳米级时,其力学性质会发生显著改变. Cu-Ni晶格失配度约为2.7%,可以形成共格界面和半共格界面,实验中实现沿[111]方向生长的调制周期为几纳米且具有异孪晶界面结构的Cu/Ni多层膜,其力学性质发生显著改变.本文采用分子动力学方法对共格界面、共格孪晶界面、半共格界面、半共格孪晶界面等四种不同界面结构的Cu/Ni多层膜进行纳米压痕模拟,研究压痕过程中不同界面结构类型的形变演化规律以及位错与界面的相互作用,获取Cu/Ni多层膜不同界面结构对其力学性能的影响特征.计算结果表明,不同界面结构的样品在不同压痕深度时表现出的强化或软化作用机理不同,软化机制主要是由于形成了平行于界面的分位错以及孪晶界面的迁移,强化机制主要是由于界面对位错的限定作用以及失配位错网状结构与孪晶界面迁移时所形成的弓形位错之间的相互作用.     

Mechanical and tribological properties of Ni/Al multilayers—A molecular dynamics study

Mechanical and tribological properties of multilayers with nanometer thickness are strongly affected by interfaces formed due to mismatch of lattice parameters. In this study, molecular dynamics (MD) simulations of nanoindentation and following nanoscratching processes are performed to investigate the mechanical and tribological properties of Ni/Al multilayers with semi-coherent interface. The results show that the indentation hardness of Ni/Al multilayers is larger than pure Ni thin film, and the significant strength of Ni/Al multilayers is caused by the semi-coherent interface which acts as a barrier to glide of dislocations during nanoindentation process. The confinement of plastic deformation by the interface during nanoscratching on Ni/Al multilayers leads to smaller friction coefficient than pure Ni thin film. Dislocation evolution, interaction between gliding dislocations and interface, variations of indentation hardness and friction coefficient are studied.     

MD simulation of nanoindentation on (001) and (111) surfaces of Ag–Ni multilayers

We perform MD simulations of the nanoindentation on (001) and (111) surfaces of Ag–Ni multilayers with different modulation periods, and find that both the hardness and maximum force increase with the increase of modulation period, in agreement with the inverse Hall–Petch relation. A prismatic partial dislocation loop is observed in the Ni(111)/Ag(111) sample when the modulation period is relatively large. We also find that misfit dislocation network shows a square shape for the Ni(111)/Ag(111) interface, while a triangle shape for the Ni(001)/Ag(001) interface. The pyramidal defect zones are also observed in Ni(001)/Ag(001) sample, while the intersecting stacking faults are observed in Ni(111)/Ag(111) sample after dislocation traversing interface. The results offer insights into the nanoindentation behaviors in metallic multilayers, which should be important for clarifying strengthening mechanism in many other multilayers.     

Molecular-dynamics simulation of the Ag/Ni interface

The atomic structure in the interface region of a Ag/Ni bicrystal is simulated by molecular dynamics. The mechanical behavior of the interface under a tensile load along the interface is also calculated. The extension of a precrack near the interface is considered. Results show that the misfit dislocations are quite important in these respects.     

Simulation study for atomic size and alloying effects during forming processes of amorphous alloys

1 Introduction Since amorphous alloys were successfully prepared by Duwez et al.[1] in the 1960s by rapid cooling from the eutectic alloy of Ag-Cu system, the investigation about atomic size and alloying effects during the formation process of amorphous alloys has become such an important area that many people paid a good deal attention. From the experiments that AgxCu1-x alloys formed amorphous structures, Takayama[2] has determined the content range of amorphous alloys, being x = 35—65, …     

Microstructures and strengthening mechanisms of Cu/Ni/W nanolayered composites

Cu/Ni/W nanolayered composites with individual layer thickness ranging from 5?nm to 300?nm were prepared by a magnetron sputtering system. Microstructures and strength of the nanolayered composites were investigated by using the nanoindentation method combined with theoretical analysis. Microstructure characterization revealed that the Cu/Ni/W composite consists of a typical Cu/Ni coherent interface and Cu/W and Ni/W incoherent interfaces. Cu/Ni/W composites have an ultrahigh strength and a large strengthening ability compared with bi-constituent Cu–X (X?=?Ni, W, Au, Ag, Cr, Nb, etc.) nanolayered composites. Summarizing the present results and those reported in the literature, we systematically analyze the origin of the ultrahigh strength and its length scale dependence by taking into account the constituent layer properties, layer scales and heterogeneous layer/layer interface characteristics, including lattice and modulus mismatch as well as interface structure.     

On the correlation between phonon spectra and surface segregation features in Ag-Cu–Ni ternary nanoalloys

Atomic scale characterization of chemical ordering, compositional distribution and microstructure is of tremendous importance for applications such as catalysis which is primarily dominated by processes occurring at surface and is strongly influenced by the subsurface layers. Phonon spectra obtained from molecular dynamics simulations of single metals as well as their bimetallic and ternary alloy nanoclusters can be used to obtain new insights into the atomic scale distribution in the nanoclusters, their microstructure and dynamical properties. Monte-Carlo (MC) simulations are used to obtain the minimum energy configurations of various Ag–Cu–Ni ternary alloys in which the Ag content is systematically varied from 0 to 50%Ag while keeping the relative composition of Cu and Ni constant. Detailed compositional analyses of the final MC configurations are carried out. The generated microstructure comprised of surface segregated structures in which Ag atoms occupy low coordination sites such as corners, edges and faces. As the Ag content in the ternary alloy is increased, the surface sites get increasingly occupied with the lowest coordination sites being populated first. The Cu and Ni compositions in the interior of the cluster show compositional oscillation. The final alloy microstructure is dictated by the competition between the various entropic and energetic factors. Our analysis of the phonon density of states identifies various surface (low frequency) and bulk (high frequency) modes which is determined by their location in the nanocluster and the local environment. Systematic trends in the observed peak intensities and frequency shifts at the low and high frequency ends of the spectrum for the various alloy compositions are explained on the basis of bond-lengths, local coordination, extent of alloying, and neighboring elemental environment. We find that the characteristic microstructural features observed at the atomic scale are strongly correlated to the vibrational densities of states of the constituent atoms in nanoalloys. Comparisons with experimental investigations are made where possible. Such a characterization method provides a predictive tool for materials which are extremely important for catalytic applications and emerging energy technologies.     

用MAEAM法计算Ag/Ni的界面能

采用改进分析型嵌入原子法计算了Ag(111)//Ni(001)和Ag(001)//Ni(111)扭转界面的能量，结果表明：对Ag(111)//Ni(001)界面，当扭转角等于0°（或30°）时界面能最小，这一择优扭转角取向和Gao等人的实验结果一致；同样，对Ag(001)//Ni（111）界面，当扭转角等于0°（或30°）时界面能最小；从界面能最小化考虑，Ag(001)//Ni(111)扭转界面的择优扭转角也为0°（或30°）. 关键词： Ag/Ni界面 界面能 计算 改进分析型嵌入原子法 近重合位置点阵     

基于多尺度模拟研究Ni/Cu薄膜压痕塑性的原子机制

基于准连续介质多尺度模拟方法研究了Ni/Cu双层薄膜初始压痕塑性的原子机制,结果主要包括:(1)当Ni晶体层厚度小于10nm时,随着Ni晶体层厚度的减少,薄膜弹性极限所对应的临界接触力逐渐降低,即Ni/Cu薄膜随Ni晶体层厚度减小而变软;(2)压头下方晶格Shockley分位错的开动、界面位错的分解、以及界面位错与晶格位错的相互作用是Ni/Cu薄膜初始塑性的微观原子机制,(3)根据模拟结果观察和位错弹性理论计算,承载初始塑性的界面位错数目变少是Ni/Cu薄膜软化的主要原子机制.本文研究结果能够为异质界面力学行为研究提供有益参考.