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。     

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   

一种高性能低偏析耐蚀合金的研究

研究了硫对Hastelloy C-4合金凝固偏析和耐蚀性的影响。结果表明，严格控制硫含量，能减小固液两相区的间隔和温度范围以及合金的偏析程度，明显改善合金耐蚀性能。     

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.     

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.     

螺旋磁场对Sn-Sb合金成分偏析的影响

为了深入研究螺旋磁场解决重力偏析的效果及作用机理,本文选用低熔点Sn-Sb合金,分析不同励磁电流下螺旋磁场对铸锭宏观成分偏析的影响,并与常规条件下及相同工艺参数旋转磁场条件下的凝固组织进行比较.结果表明,螺旋磁场的电磁力分布特点有利于在铸锭内部形成更大区域的均匀搅拌,相比于旋转磁场可以更好地改善铸锭成分的宏观偏析;随着励磁电流的增大,两种磁场改善偏析、细化凝固组织的效果更好;当螺旋磁场励磁电流为100 A时,基本消除铸锭上、下部位由于重力作用导致的成分偏差,β相(SnSb)变得细小且均匀分布在基体内.在金属熔体凝固的过程中施加螺旋磁场可消除重力偏析,效果优于旋转磁场.     

磁控共溅射Ni3 Al合金薄膜的微观结构及电阻特性

研究了室温下采用直流磁控共溅射法在抛光玻璃和Si基底上沉积Ni3Al合金薄膜的制备工艺、微观结构和电阻特性.采用SEM、EDX、AFM、TEM等测试分析了不同基底、溅射功率、工作气压等因素对薄膜微观结构、成分比和电阻特性的影响.结果表明:采用大功率混合溅射可以得到多晶态Ni3Al纳米合金薄膜,且呈多层岛状生长.所得薄膜具有良好的导电性,与玻璃相比,在Si基底上的薄膜表面光滑平整,晶粒更小,电阻率略大.然而随着厚度的减小,薄膜的电阻率增加迅速,发生金属向绝缘体过渡的相变,而厚度较大时这种现象不明显,这表明Ni3Al薄膜相变与厚度及晶格中氧含量有关.     

Material properties of Au-Pd thin alloy films

Thin films of Au-Pd of varying composition were formed by electron beam physical vapor deposition. They were characterized and their application as optical hydrogen sensors was studied. In addition, parameters of sensing performance such as Pd deficiency during deposition, grain size, compositional homogeneity, and the appearance of a natural buffer layer, were examined. Following deposition, Au-Pd films exhibited high atomic intermixing, and a PdO_x buffer layer formed spontaneously. This layer makes it possible to increase film thickness, which improves the intensity of the detecting signal. Accordingly, the suggested deposition method may optimize recent efforts to use Au20 wt.%-Pd thin alloy film in optical hydrogen sensors.     

磁控溅射Ni-Mn-Ga薄膜的磁致应变

采用直流磁控溅射的方法,在NaCl基底上沉积了Ni-Mn-Ga薄膜,对薄膜进行了形貌观察、微区成分及结构分析,并测量了薄膜的磁致应变.结果表明,薄膜表面可见大小不一的团簇颗粒,具有明显的岛状结构,表明Ni-Mn-Ga薄膜的形成为典型的核生长型机制.热处理前的薄膜具有部分非晶存在,热处理后薄膜晶化为多晶形态.无约束薄膜在磁场下呈现负的磁致应变,在1.3T磁场下,其最大应变值可达-0.008%,并且可以完全恢复.     

Surface segregation and preferential sputtering in thin Al–Ni alloy films

The surface composition of Al_xNi_1−x alloy films was studied by X-ray electron spectroscopy (XPS) after various surface treatments and oxidation at room temperature. Ion etching caused a marked enrichment in Ni of the altered surface layer. After extensive sputtering, bombardment-induced segregation of Al at the outermost surface layer of the films was established. Al segregation to the surface was observed during annealing up to 1200 K. The interaction of oxygen with the surface of the alloy films caused surface segregation of Al, accompanied by preferential oxidation of Al.     

Modeling of metastable phase formation diagrams for sputtered thin films

A method to model the metastable phase formation in the Cu–W system based on the critical surface diffusion distance has been developed. The driver for the formation of a second phase is the critical diffusion distance which is dependent on the solubility of W in Cu and on the solubility of Cu in W. Based on comparative theoretical and experimental data, we can describe the relationship between the solubilities and the critical diffusion distances in order to model the metastable phase formation. Metastable phase formation diagrams for Cu–W and Cu–V thin films are predicted and validated by combinatorial magnetron sputtering experiments. The correlative experimental and theoretical research strategy adopted here enables us to efficiently describe the relationship between the solubilities and the critical diffusion distances in order to model the metastable phase formation during magnetron sputtering.     

铝掺杂对非晶SiOx薄膜电致发光的影响

为提高硅基薄膜（SiOx）发光材料的发光效率，采用双离子束溅射法制备了不同铝含量的Al—Si—SiOx薄膜。对所制备样品的电致发光（EL）测试表明：由于金属（Al）的掺入，使得在同样的电压下。薄膜中的电流随着铝含量的增加而增加；并且铝含量增大使得通过薄膜的电流增强，因而得到较高强度的电致发光。所以当硅基薄膜中掺入铝时，薄膜的发光效率得以提高；并且，随着铝含量的增加，薄膜的发光效率亦相应提高。