短纤维增强铝铜二元合金复合材料凝固偏析的数值模拟

根据凝固过程中的守恒原理,建立了铝基复合材料凝固过程的数学模型.根据所建立的模型对氧化铝短纤维增强铝铜二元合金复合材料进行数值模拟,模拟结果表明:氧化铝短纤维周围有低熔点物质及溶质富集;随冷却速度增大,复合材料基体偏析加剧;随复合材料中纤维体积分数增大,基体中偏析减小.     

表面偏析浓度非连续变化现象的定量解释

本文利用修正的Darken模型,对合金体系表面偏析浓度随温度和体浓度非连续变化现象给予了定量的解释,并对Cu(111)Ag合金中,表面偏析浓度随银体浓度变化的实验数据进行了拟合,获得了相应的表面偏析参数。     

离子束合成TiO2薄膜对医用NiTi合金表面的改性

采用离子束增强沉积法制备TiO2薄膜,对医用NiTi合金进行表面改性处理。系统研究了薄膜的表面组成、结构、形貌及耐蚀性、亲水性等与血液相容性相关的表面性质。NiTi合金表面沉积TiO2薄膜后,抗模拟体液的腐蚀性提高,凝血时间延长。为进一步提高TiO2薄膜的抗凝血性,对TiO2薄膜的进一步表面改性－表面结合肝素分子进行了初步尝试,结果表明,薄膜表面组成发生变化,表面亲水性进一步提高。     

基片表面粗糙度对坡莫合金AMR以及磁性能的影响

利用霍尔离子源轰击Si基片获得了不同表面粗糙度的基片,然后利用磁控溅射方法制备了一系列Ta(5nm)/Ni 80Fe 20(12nm)/Ta(2nm)薄膜样品,重点研究了基片表面粗糙度对薄膜结构和各向异性磁阻效应的影响。采用AFM测量基片的表面粗糙度,采用四探针法测量薄膜的各向异性磁阻效应。研究结果表明,随着基片表面粗糙度的增加,坡莫合金的AMR值显著降低,且ΔH显著增加。     

Fe-Ni合金薄膜组成表面分析测量国际

利用X射线光电子能谱技术,建立了Fe-Ni合金薄膜组成表面分析准确定量方法,中国计量科学研究院参加了国际关键比对CCQM-K67。根据最近公布的关键比对结果,中国计量科学研究院测量的Fe原子分数结果为51.48%,与参加的各国国家计量研究院的结果（50.02%）达到了等效一致。     

表面机械研磨处理对Cu-10wt％Ni合金组织及性能的影响

对Cu-10％(质量分数)Ni合金进行表面机械研磨处理,采用X射线衍射仪、光学显微镜、显微硬度测试仪等对处理不同时间样品的组织及性能进行了分析.结果表明表面机械研磨处理后,Cu-10％(质量分数)Ni合金实现了表面纳米化.处理时间30min时,表面晶粒尺寸为42.92nm,随着处理时间的延长,晶粒逐渐细化,强烈变形层逐...     

La 对非晶 Ni_(63)Zr_(37)合金表面状态的影响

采用俄歇电子能谱和 X 射线光电子能谱,并结合氩离子原位溅射剥层研究了非晶 Ni_(63)Zr_(37)及Ni_(63)Zr_(32)La_5合金条带自由侧和贴辊侧的表层成分分布及元素的化学状态。结果表明,非晶 Ni_(63)Zr_(37)合金条带贴辊侧氧化层较自由侧厚且 Zr 的表面偏聚较为显著;加入 La 后,显著地改变了 Ni_(63)Zr_(37)合金条带两侧的表面状态;在合金条带表面及近表面,Ni 以金属态弥散分布在 Zr 和 La 的氧化物上,其电子状态受氧化物的影响;条带表层 Zr 的氧化物由 ZrO_x(1相似文献   

沉积温度对化学气相沉积法制备铜薄膜性质的影响

以双(2,2,6,6-四甲基-3,5-庚二酮)化铜(Cu(DPM)₂)为前驱体,使用智能化学气相沉积设备在673 K至1173 K下于AlN多晶基板上制备Cu薄膜。研究了不同沉积温度对Cu薄膜的相组成、择优取向、宏观表面、微观结构、元素组成及电导的影响。在873 K至1173 K时制备了具有(111)择优取向的紫铜色铜薄膜,同时存在(200)和(220)取向,且铜晶粒呈岛状生长模式。随着沉积温度的升高,薄膜的导电性先增强后减弱。在1073 K时,制得了导电性最好且高度(111)择优取向的最纯紫铜色Cu薄膜,即1073 K为制备Cu薄膜的最佳沉积温度。     

气体吸附诱导Cu(Au)合金中Au原子的偏聚和富集

合金中的表面成分和相偏析会改变其功能,尤其是在表面结构和化学起着至关重要作用的应用中.例如,合金催化剂的表面状态显著影响其在异相催化和电化学过程中的催化性能.表面成分偏析被认为是由表面能的差异驱动,以减少合金体系的总自由能.然而,目前合金中成分偏析的原子尺度进程还尚不清楚,尤其是对于气体分子诱导的成分偏析,在该过程中可能同时发生结构和化学重排.本文通过像差校正环境TEM从原子尺度研究了固溶态Cu(Au)合金在CO气氛下的表面偏析行为. CO气氛能够诱导Cu(Au)合金表面形成有序结构,在很大程度上改变合金的表面化学性质.高温条件下, CO气氛会进一步促进Au原子通过特定的"原子通道"进行扩散,在合金表面偏聚和富集.富集形成的Au纳米颗粒与合金表面在形貌和结构方面发生了丰富的动力学交互作用.这其中CO气体吸附也起着重要的作用.这些原子尺度的研究结果为双金属合金的表面偏析和去合金化机理提供了直接证据,并突出了气体吸附物在这些表面行为中的作用.     

行波管放大链中关键气密材料的失效分析

行波管放大链中关键气密材料的气密性与行波管放大链的性能有密切的联系,分别用IRS、XRD、XPS、SEM和EDS等对该气密材料镍铜合金进行了一系列的失效分析,对影响其气密性的因素做了相应的探讨.结果表明:锰的氧化物在晶界处析出会明显弱化镍铜合金的晶界内聚力,进而致使晶间发生断裂,气密性变差.     

Atomic and electronic structure of both perfect and nanostructured Ni(111) surfaces: First-principles calculations

In this study, we perform first principles simulations on both atomically smooth and nanostructured Ni(111) slabs. The latter contains periodically distributed nickel nanoclusters atop a thin metal film gradually growing from adatoms and serving as a promising catalyst. Applying the generalized gradient approximation within the formalism of the density functional theory we compare the atomic and electronic structures of Ni bulk, as well as both perfect and nanostructured (111) surfaces obtained using two different ab initio approaches: (i) the linear combination of atomic orbitals and (ii) the projector augmented plane waves. The most essential inter-atomic forces between the Ni adatoms upon the substrate have been found to be formed via: (i) attractive pair-wise interactions, (ii) repulsive triple-wise interactions within a triangle and (iii) attractive triple-wise interactions within a line between the nearest adatoms. The attractive interactions surmount the repulsive forces, hence resulting in the formation of stable clusters from Ni adatoms. The magnetic moment and the effective charge (within both Mulliken and Bader approaches) of the outer atoms in Ni nanoparticles increase as compared to those for the smooth Ni(111) surface. The calculated electronic charge redistribution in the Ni nanoclusters features them as possible adsorption centers with increasing catalytic activity, e.g., for further synthesis of carbon nanotubes.     

Hydrogen gas sensing performance of Pd-Ni alloy thin films

We investigated the hydrogen (H₂) sensing properties of palladium (Pd)-nickel (Ni) alloy films with varying Ni content and discussed them in light of structural deformations. The Pd-Ni alloys operated reversibly upon H₂ absorption and desorption and their sensitivities decreased linearly with Ni content added to Pd. This was attributed to reduction in the lattice constant and interstitial volume caused by the Ni addition, allowing fewer hydrogen atoms to penetrate into the Pd-Ni alloy with higher Ni content. Interestingly, the response time of the Pd-Ni alloys was much shorter than that of pure Pd, presumably due to the fast permeation of hydrogen atoms through microscopic imperfections in the alloys. Unlike pure Pd, the Pd-Ni alloys showed an almost linear relationship between the sensitivity and H₂ concentration without hysteretic behaviors, enabling the detection of low concentration of H₂ down to 0.01%. These results provide a significant understanding of the role of Ni in the Pd-Ni thin films for improving the H₂ sensing properties of the Pd-based alloy film sensors.     

用于高频声表面波器件的CVD金刚石衬底的研究

使用纳米金刚石粉研磨工艺预处理硅片衬底抛光面,在低气压成核的条件下,以丙酮和氢气为反应物,采用传统的热丝辅助化学气相沉积法,制备了自支撑金刚石膜;通过射频磁控溅射法沉积氧化锌薄膜在自支撑金刚石膜的成核面,形成氧化锌/自支撑金刚石膜结构.通过光学显微镜、扫描电镜及原子力显微镜测试自支撑金刚石膜成核面的表面形貌.研究结果表明:成核期的低气压有助于提高成核密度,成核面表面粗糙度约为1.5 nm;拉曼光谱显示1334 cm-1附近尖锐的散射峰与金刚石SP3键相对应,成核面含有少量的石墨相,且受到压应力的作用;ZnO/自支撑金刚石膜结构的XRD谱显示,氧化锌薄膜有尖锐的(002)面衍射峰,是c轴择优取向生长的.     

(Ni0.81Fe0.19)0.66Cr0.34/Ni0.81Fe0.19薄膜的各向异性磁电阻效应及尺寸效应

研究了以非磁性（Ni0.81Fe0.19)0.66Cr0.34薄膜作为过渡层的坡莫合金Ni0.81Fe0.19薄膜的磁电阻效应和饱和磁场,分析退火处理对样品饱和磁场的影响和经刻蚀后的磁电阻效应膜线的尺寸效应,并建立一个统计模型定性分析了其性能变化的机理,计算结果符合实验。     

The Surface Tension of Binary Alloys: Simple Models for Complex Phenomena

Surface segregation is the key to understanding the surface tension γ of alloys. The basic phenomena can be demonstrated qualitatively by using the ideal solution model. For a binary system, this model is first used to explain the temperature dependence of the surface tension. A simple criterion is established for sign reversal of the temperature coefficient. The ideal solution model is then extended to include the effect of compound formation. A simple explicit equation is proposed which fits existing data surprisingly well. Paper presented at the Seventh International Workshop on Subsecond Thermophysics, October 6-8, 2004, Orléans, France.