Cu-Ni合金结构的分子动力学模拟

采用EAM作用势对Cu Ni合金的结构特性进行了MD模拟研究 .通过FZ结构因子可发现 ,Cu含量的变化对结构因子的波动影响很小 ,键取向序参数和键对也表现出相似的变化规律 ,这表明液态Cu Ni合金对成份变化不敏感 ,体系中的化学序较弱 .将Cu70 Ni3 0 合金熔体的FZ结构因子与Waseda的实验结果进行对比 ,发现二者吻合得较好 ,表明EAM势可以很好地描绘Cu Ni合金的结构特性 .在快速冷却过程中 ,除了Cu2 0 Ni80 合金外 ,其他合金成份的双体分布函数的第二峰都发生了劈裂 ,标志着体系最终形成了非晶结构 ,而Cu2 0 Ni80 合金的双体分布函数却表现出晶体峰的特征 .通过对键取向序参数、键型指数以及铜镍原子的有效扩散系数的分析表明 ,在快速冷却过程中 ,Cu2 0 Ni80 合金最终形成了hcp晶体结构     

Cu50Ni50合金快速凝固的分子动力学模拟

采用分子动力学模拟的方法研究了Cu₅₀Ni₅₀合金在不同冷却速度下的凝固过程,利用均方位移、径向分布函数和结构可视化等方法分析其微观结构.并对凝固模型进行拉伸模拟,通过应力应变曲线和直观结构变化分析其性能.研究表明：冷却速度对Cu₅₀Ni₅₀合金凝固形成的结构有较大影响,随着冷却速度的升高,凝固形成的结构中晶体含量减少,在较低的冷却速度下,如冷却1×10¹²K/s时,Cu₅₀Ni₅₀合金凝固形成晶体结构;在较高的冷却速度下,如1×10¹⁴K/s时,Cu₅₀Ni₅₀合金凝固形成非晶体结构,且非晶Cu₅₀Ni₅₀合金的抗拉性能要优于晶体Cu₅₀Ni₅₀合金.     

ICP-AES法测定镍基、铁镍基高温合金与结构钢中的微量硼

本文采用ＩＣＰ－ＡＥＳ法对镍基、铁镍基高温合金与结构中微量硼元素的测定进行了研究,着重考察了镍基ＤＺ１２５合金,铁镍基ＧＨ４１６９合金和结构钢的基体与合金元素对硼含量测定的影响,采用了分步沉淀分离方法,消除了铁（基体）、钨和铌,钽（合金中共存元素）对硼的干扰,测定了样品中微量硼,取得了满意的结果。     

Effect of alloying and temperature of deformation on the grain structure and phase composition of Ni3Al intermetallic

The structure of Ni₃Al intermetallic alloyed with boron and hafnium is studied at various temperatures of deformation by means of diffraction and scan electron microscopy. The alloy was produced through self-propagating synthesis. The phase composition of the alloy is determined. The effect of doping with boron and hafnium on the alloy structure morphology is revealed.     

Structure in surface frictional layers on 36NKhTYu alloy

A study has been made on how heat treatment affects surface-layer formation and structure in unlubricated friction on steel 45 for high-tensile austenitic 36NKh-TYu alloy. The substructure formed in the friction zone has multiple continuous and discrete orientation deviations and is independent of the initial alloy state. However, the aged alloy differs from the quenched in that there is turbulence in the surface-layer structure.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 9–12, August, 1991.We are indebted to Yu. V. Svitich for a discussion.     

Electronic theory of the chemisorption effect on surface segregation in transition-metal alloys

The tight-binding Ising model generalized for a system consisting of a transition-metal alloy with chemisorbed adatoms is used to calculate the effect of hydrogen chemisorption on surface segregation in a Cu---Ni alloy. The simple model of chemisorption and of the band structure of the alloy is assumed. The charge-neutrality condition is incorporated into the model.     

非晶态Mg_(70)Zn_(30)合金结构因子的预峰

利用X射线衍射仪对非晶态Mg70 Zn30 合金的结构进行了研究 ,获得了强度曲线、结构因子、双体分布函数和原子间最近邻距离 .结果表明 ,Mg70 Zn30 合金在小Q区间存在强烈的预峰现象 .根据预峰的特性 ,提出了Mg70 Zn30 熔体的结构模型 ,即Mg原子位于中心 ,8个Zn原子位于顶角所形成的简单立方结构模型 .该模型以共享顶点的方式相连接 ,能够满足预峰对Mg—Mg原子间距离的要求 .Mg70 Zn30 非晶合金中预峰的产生是相邻原子团中心Mg原子之间相互关联的表现     

Non-Bloch nature of alloy states in a conventional semiconductor alloy: GaxIn1-xP as an example

Using GaxIn1-xP as a prototype system, we present the first systematic examination of the alloy scattering effects on the global electronic structure of a semiconductor alloy for the whole composition range. Contrary to conventional wisdom, many electronic states in such a "well behaved" alloy are found to differ drastically from a Bloch state, including band edge states that are derived from degenerate critical points. This study offers a more comprehensive picture of the electronic structure of the alloy, and reveals new nontrivial but vital implications of the alloy scattering on transport and optical properties.     

Structure and composition of the NiPd(1 1 0) surface

The NiPd(1 1 0) alloy surface was studied using low energy electron diffraction to measure the structure and composition of the first three atomic layers. The surface layer is highly enriched in Pd and has a significantly buckled structure. The second layer is also buckled, with displacements even larger than the surface layer. The second layer also exhibits intralayer segregation (chemical ordering), with alternate close-packed rows of atoms being Ni enriched and Pd enriched. The third layer has a structure and composition close to that of the bulk alloy. These results are compared with results for the other low index faces of NiPd, the extensive literature on NiPt alloy surfaces, and the growing body of theoretical literature for NiPd alloy surfaces.     

Macrosegregation driven by movement of minor phase in (Al0.345Bi0.655)90Sn10 immiscible alloy

Formation of macrosegregation structure in (Al_0.345Bi_0.655)₉₀Sn₁₀ (mass percent, the same below) immiscible alloy was investigated by spraying its melt into silicone oil. Two kinds of typical macrosegregation structures were obtained in the dispersed alloy spheres: core/shell structure and crescent structure. Based on the estimated temperature field inside the alloy spheres, the velocities of thermal Marangoni, solutal Marangoni, and Stokes motions of the Bi-rich minor droplets were calculated. Analysis shows that surface segregation, Soret effect, thermal Marangoni motion, solutal Marangoni motion, and Stokes motion play a key role in the formation of Al/Bi–Sn core/shell structure. If the liquid alloy spheres solidify on the condition that the radius of the Bi-rich minor droplets is smaller than a critical value, it will form Al/Bi–Sn core/shell structure, while the crescent structure will be formed when the liquid alloy spheres frozen on the condition that the radius of the Bi-rich minor droplets exceeds the critical value.     

Modification of properties of aluminum protective anodes by nanopowder materials

Experimental study was performed on the influence of nanosized refractory nanopowders on the structure and electrochemical characteristics of aluminum alloy AlZn4 used as protective anode. It was found that modification of alloy AlZn4 with nanopowder of aluminum nitride or diamond induces refining of alloy structure by the factor of 1.5, increases the anode strength and its protective negative potential. Those factors have practical value for higher efficiency of protection from corrosion in water-contacting vessels.     

The evolution of coordination structure in liquid GaSn alloy

The dynamic viscosity and the liquid structure of Ga₉₈Sn₂ alloy melt at different temperatures were measured by a torsional oscillation viscometer and an x-ray diffraction. The viscosity of the liquid Ga₉₈Sn₂ alloy increases with decreasing temperature and an obvious turning point is observed on the Arrhenius curve. The breakpoint in Arrhenius plot emerges when the structure of Ga₉₈Sn₂ alloy melt is transformed from the high coordinated polyhedron clusters to the low coordinated polyhedron clusters. It is found that the change of the viscosity is a characteristic of microstructure transformation in the alloy melt.     

Al_xCrFeNiTi系高熵合金成分和弹性性质关系

为了探索Al_xCrFeNiTi系高熵合金组成成分和弹性性质的关系,结合固溶体特征参数和第一性原理计算,研究Al元素含量对Al_xCrFeNiTi (x=0, 0.5, 1, 2, 3, 4)合金结构和弹性性质的影响,并分析合金固溶体特征参数与弹性性质之间的关系.结果表明:Al_xCrFeNiTi系合金的价电子浓度随着Al含量的增加逐渐减小,合金在体心立方结构下的形成焓均低于面心立方结构,说明研究的Al_xCrFeNiTi系合金会形成单一的体心立方结构固溶体;合金的晶格常数和形成能力强弱随着Al含量的增加而增大,但合金的结构稳定性略有下降;当合金元素按照等原子比进行成分配比时,合金的原子尺寸差异最大; Al_xCrFeNiTi系合金中不同原子之间除了金属键结合外,还表现出一定的共价和离子键结合特征;对于Al_xCrFeNiTi系合金而言,随着热力学熵焓比的增大,合金体弹模量和韧性随之增大;随着合金混合焓的增加,合金在压缩方向的各向异性程度明显降低.热力学熵焓比和混合焓可作为Al_xCrFeNiTi系高熵合金成分设计的重要参数.     

Features of Forming a Structure of the Copper-Zinc Alloy Coating on the Aluminum Alloy Surface by Friction Stir Processing

Russian Physics Journal - The structure of samples of the C27400 copper alloy coatings on the AA5056 aluminum alloy surface, produced by friction stir processing of a rolled sheet package is...     

Alloy model for high-temperature superconductors

An alloy model is proposed for the electronic structure of high-temperature superconductors. It is based on the assumption that holes and extra electrons are localized in small copper-oxygen clusters, that would be the components of such an alloy. This model, when used together with quantum chemical calculations on small clusters, can explain the structure observed in the experimental densities of states of both hole and electron superconductors close to the Fermi energy. The main point is the strong dependence of the energy level distribution and composition on the number of electrons in a cluster. The alloy model also suggests a way to correlate T_c with the number of holes, or extra electrons, and the number of adequate clusters to locate them.     

Effect of alloying with boron on the phase composition and structure of Ni3Al

The structure of Ni₃Al alloy prepared by self-propagating high-temperature synthesis is studied by means of transmission electron diffraction, scanning microscopy, and X-ray structural analysis. The effect of alloying with boron on the morphology of the alloy structure is established. The grain and defect structures are investigated. The dislocation density and the internal stress are measured.     

Co-B非晶态合金中电子转移问题的量子化学研究

根据Co -B非晶态结构的短程有序、Co和B之间是较强的化学作用以及化学键理论 ,设计了ComB2 (m=1～ 4)原子簇模型 ,用DFT方法对其进行高水平的量子化学计算 ,结果表明 ,模型体系ComB2 (m =1～ 4)中 ,B原子供给Co原子电子 ,这与非晶态合金的实验结果一致 ,同时存在B -B直接相连 ,为了比较 ,也选择了ConB (n =1～ 4)模型 ,计算结果与实验不符 ,说明ComB2 (m =1～ 4)原子簇模型更能反映非晶态的结构特点 .     

基于光谱特征分析的光纤光栅腐蚀传感器研究

针对航空航天领域铝合金结构服役过程腐蚀监测需求,提出了一种基于铝质细管结构的预载荷型光纤光栅腐蚀传感器。给出了铝合金结构腐蚀在役监测机理,得到光纤光栅反射光谱特征与铝质细管厚度变化之间的理论关系模型,构建了酸碱环境下的光纤光栅腐蚀监测试验系统。通过在细管内部配置不受力且仅感受温度变化的光纤光栅传感器,解决了被测目标的温度与应力交叉敏感问题。研究表明,这种铝质细管封装设计不仅可以感受腐蚀对其力学性能的影响,还能够屏蔽外界腐蚀因素对管内光纤感知器件的干扰。随着金属管腐蚀程度加深,其管壁逐渐变薄,光纤光栅反射光谱逐渐向短波长方向偏移,且管壁厚度变化与光栅中心波长偏移量之间呈较好单调关系。这些特性能够为进一步开展基于光纤感知器件的机械结构在役腐蚀监测研究提供有益帮助。     

Effect of rotating magnetic field on microstructure formation of directionally solidified Sn–1.6Cd peritectic alloy

In order to investigate the effect of rotating magnetic field on the microstructure formation of peritectic alloys, directional solidification experiments of Sn–1.6Cd peritectic alloy have been conducted under different rotating magnetic field conditions. The directional solidification microstructure of Sn–1.6Cd peritectic alloy changes from banded structure to axisymmetric isolated banded structure to axisymmetric oscillatory tree-like banded structure and to single primary phase structure when the magnetic Taylor number of forced-melt flow generated by a rotating magnetic field increases from 0 to 91 to 364 and to 1456. The second and third banded structures are observed in a peritectic alloy for the first time. The results indicate that it is possible to control solidification microstructure and prepare a single primary phase structure by using a rotating magnetic field during directional solidification of peritectic alloys. The experiments show that the effect of forced-melt flow on solute distribution transforms from solute buildup to homogenization with an increase in the magnetic Taylor number. The formation mechanisms of those structures are also discussed.     

非晶物质中的临界现象

非晶态材料有着复杂的原子结构(短程有序、长程无序)和特殊的物理性质,其临界现象和相变问题一直受到学术界关注.非晶合金,又称为金属玻璃,是一种新型的非晶态材料,具有很高的强度和优异的弹性.从微观的角度来看,非晶合金可以看作是一个多粒子系统.临界现象的研究对认识和理解多粒子系统之间的相互作用有深刻的意义.本文主要讨论非晶合金中的临界现象,包括非晶合金从制备过程、微观结构到宏观的力学性能以及磁性方面存在的临界现象,并分析这些临界现象之间的内在联系,进而深入理解非晶合金的微观结构对其宏观性质的影响.这为认识非晶合金的形成本质,提高服役可靠性,探索具有实际应用价值的非晶合金提供理论依据.