Ordering properties and interpretation of radiation damage IN Au–15 at.% Ag alloys

The equilibrium value of the electrical resistivity of Au–16.25 at.% Ag has been determined as a function of temperature. In addition, isochronal annealing of quenched Au–15 at.% Ag alloys has been studied by means of resistivity measurements. Both types of experiments indicate that in these alloys a decrease of the degree of order gives rise to an increase of the electrical resistivity. This result confirms the previous interpretation of the radiation damage and its recovery in low-temperature electron-irradiated Au–15 at.% Ag alloys in terms of the two-interstitial model.     

Correlation study of structural,electrical and mechanical properties of quenched tin–zinc–cadmium solder alloys

It is important, for electronic application, to decrease the melting point of SnZn₉ solder alloy because it is too high as compared with the most popular eutectic Pb–Sn solder alloy. Adding Cd causes structural changes such as phase transformations, dissolution of atoms and formation of Cd crystals in the quenched SnZn₉ alloy, and its physical properties are affected by this change. For example, the melting point is decreased towards the melting point of the Pb–Sn eutectic alloy, or even much less. The structure, electrical and mechanical properties of quenched Sn_{91? x} Zn₉Cd _x (x?=?0 or x?≥?5) alloys have been investigated. Adding Cd to a quenched SnZn₉ alloy increases its electrical resistivity and decreases its elastic modulus and internal friction. The Sn₇₁Zn₉Cd₂₀ alloy has the lowest melting point (162 °C) and electrical and internal frictions as compared with commercial Pb–Sn solder alloys.     

Superconducting proximity effect in Ag—Mn

The proximity effect was studied by measuring the thermal conductivity of double layers films made of a normal metal (Ag or Ag—Mn) and a superconductor (Pb–5% Bi), in the temperature range of 0.3–2 K.Thermal conductivity ratios have been used to estimate induced energy gap in silver and in dilute silver manganese alloys. No evidence for bound states in the presence of magnetic impurities was observed.     

Microstructure and physical properties of bismuth–lead–tin ternary eutectic alloy

Using different experimental techniques, microstructure, electrical resistivity, attenuation coefficient, and mechanical and thermal properties of the quenched Bi–Pb–Sn ternary eutectic alloy have been investigated. From the X-ray analysis, Bi₃Pb₇ and Bi–Sn meta-stable phases are detected, in addition to rhombohedral bismuth and Sn body-centered tetragonal phases. This study also compared the physical properties of the Bi–Sn–Pb ternary eutectic alloys with the base binary Bi–Sn and Bi–Pb eutectic alloys.     

Structural Features of Pseudoalloys Formed in the Course of Explosive Compaction of Ni–Ag and Fe–Pb Bimetallic Nanoparticles

Russian Physics Journal - The paper examines the bulk nanostructured alloys (pseudoalloys) produced by method of shock-wave impact upon Ni–Ag 9 wt% and Fe–Pb 27 wt% bimetallic...     

A Mössbauer study of amorphous ytterbium — Noble metal alloys: Short-range order versus dense random packing

Amorphous alloys Yb₈₀X₂₀ (X=Cu,Ag,Au) have been investigated by¹⁷⁴Yb Mössbauer spectroscopy. Samples have been prepared by sputtering and by roller quenching for all 3 alloys. For the materials studied, the distribution of the quadrupole splitting parameter δ_Q and of the asymmetry parameter η, corresponds to the distribution expected for a dense random packing model. No significant differences between the results for quenched and for sputtered samples were found.     

Effect of solute atoms on fracture toughness in dilute magnesium alloys

The effect of alloying elements on the toughness and the fracture behaviour was investigated on seven kinds of Mg-0.3?at.% X (X?=?Ag, Al, Ca, Pb, Sn, Y and Zn) alloys with a grain size of 3–5?μm. The fracture toughness and fracture behaviour in magnesium alloys were closely related to the segregation energy. The Mg–Al and –Zn alloys that had small segregation energy showed high toughness and ductile fracture in most regions, while the Mg–Ca alloy with large segregation energy exhibited low toughness and intergranular fracture. These different tendencies resulted from solute segregation at grain boundaries (GBs). The change in the lattice parameter ratio was the influential material parameter regardless of whether the GB embrittlement was for enhancement or suppression.     

A survey of surface tension,molar volume and density for Sn–Ag–Cu–Bi–Sb quinary alloys as lead-free solders

ABSTRACT

By applying the geometric models and the theoretical equation, the surface tension, the molar volume and the density were studied. The empirical calculations were carried out in temperature range 623?K?≤?T?≤?1123?K. Only few thermophysical properties were estimated for eight quinary alloys: Sn3.55Ag0.5Cu3Bi3Sb, Sn3.48Ag0.5Cu3Bi5Sb, Sn3.48 Ag0.5Cu5Bi3Sb, Sn3.40 Ag0.5Cu5Bi5Sb, Sn3.53Ag1Cu3Bi3Sb, Sn3.46Ag1Cu3Bi5Sb, Sn3.46Ag1Cu5Bi3Sb, Sn3.38Ag1Cu5Bi5Sb. The results show that surface tension and density have a linear appearance for all temperatures. We have also studied the influence of the composition and temperature in the studied alloys. The obtained theoretical results are compared with the experimental ones and with the conventional Pb–Sn welds.     

金/银纳米颗粒对Eu掺杂薄膜发光特性影响的研究

本文将三种金属纳米颗粒(球形银纳米颗粒、三角形银纳米薄片和三角形金纳米薄片)分别置于Eu(TTFA)3掺杂的Su8薄膜上研究了它们对铕配合物薄膜发光的影响.结果显示,金属纳米颗粒的局域等离子体共振(LSPR)谱对薄膜发光有很好的调控作用.对于LSPR谱分别与铕配合物激发谱和辐射谱重叠较好的球形和三角形两种银颗粒,相比于未放置颗粒时薄膜的发光,放置有颗粒的发光有明显的增强,其中球形银颗粒的样品的发光增强效果更为明显.而对于LSPR谱与铕配合物激发谱和辐射谱都不重叠的三角形片状金颗粒,该颗粒对样品的发光则起到了猝灭作用.     

Tunneling characteristics of trilayer tunnel junctions

We report here the tunneling characteristics (d²V/dI²) of trilayer junctions of the form AlOxAgCuPb and AlOxCuAgPb. The Cu and Ag thicknesses both being 300 Å and the Pb thickness being 3000 Å. The two contributions to the tunneling density of states seen are: (i) the interference effect in the two normal layers showing structures associated with the Pb phonons [1]. This structure is very similar to the one of AlOxAgPb (or AlOxCuPb where the Ag (or Cu) thickness is 600 Å thus showing that the interference effect takes place in both normal metals, (ii) the induced pair potential in the normal layers produces a structure associated with the normal metal phonons. However, only the normal phonons of the metal next to the oxide are seen thus showing that the electron tunneling is a very local probe.     

Electrical resistivity of amorphous alloys

Amorphous alloys of Ga, Sn, Pb and Bi with Cu, Ag and Au are produced by evaporation on a cold substrate. The residual resistivity, the temperature dependence of the resistivity, the transition temperature of superconductivity and the temperature of the amorphous-crystalline transformation are measured. We observe e.g. that the residual resistivity increases with the noble metal concentration, and that the temperature coefficient of the resistivity of the Au alloys is always negative. In these two respects amorphous alloys differ in behaviour from the corresponding liquid alloys. These observations can be correlated with the atomic energy levels of the free atoms.     

急冷Ag-Ge二元系合金的相关系

用X射线衍射和热学分析的方法研究了急冷(冷却速度约为10⁴K/s)Ag-Ge二元系样品的相关系。由于急冷Ge在Ag中的溶解度由平衡下的1.5at％扩展到8at％。在Ge含量为8—23at％的样品中,除含Ge在Ag中的过饱和固溶体和Ge外,还有一个具有与Ag基过饱和固溶体相同成分,不同堆垛形式的亚稳相,属A3型六角密排结构,点阵常数a=2.893±0.010?,c=4.720±0.010?,c/a=1.632。用DuPont公司1090系列的差示扫描量热仪(DSC)研究了过饱和固溶体和 关键词：     

Influence of alloying elements on structure and some physical properties of quenched Sn–Sb alloy

We study the influence of ternary and quaternary alloying elements (Pb, Cd, Cu or Cu–Pb and Cu–Cd) on structural, electrical, hardness and other mechanical properties of Sn–Sb alloys (using an X-ray diffractometer and optical microscope, the double bridge method, Vickers hardness tester and the dynamic resonance method) to produce the best alloy for bearing applications. Adding Cu or Pb to Sn–Sb alloys improves their bearing properties, such as the mechanical properties (elastic modulus, internal friction, hardness and fracture strain) and thermal conductivity. Also, adding Cu, Pb or Cu–Pb to Sn–Sb alloys makes them excellent in their bearing applications and environmental hazards when compared with the Pb ₈₈Sn ₁₀Cu ₂ alloy for automotive applications (FIAT Normalizzazione) and the lead-based Babbitt bearing alloy.     

Evidence for microporosity and dislocations in Pb(Cd) alloys from positron annihilation studies

The temperature dependence of lineshape parameters obtained from Doppler profile measurements (from 7 to 350 K) is presented for rolled and unrolled Pb, Pb(Cd), and Pb(Tl) alloys. It is demonstrated that positrons can be used to detect microporosity and dislocations in Pb(Cd) alloys. The porosity is greatly reduced by rolling. Positron trapping by the Pb(Cd) alloys in the as-worked state is attributable to dislocations.     

Search for localized phonon modes inlead-based alloys by superconducting tunneling

To investigate the appearance of localized phonon modes, superconductive tunneling was performed into films of Pb_0·9M_0·1 (M = Ag, Cd, Ga, Ge, In, Mg, Mg, Sb, Sn, Te, Zn) and Pb_0·97Sn_0·03. The films were quench-condensed and later annealed at 30, 100 and 300°K. Structure in tunneling curves resulting from localized phonons was observed only for a well annealed In alloy film. For most of the impurities an absence of observable local phonon modes could be explained as due to a lack of solid solubility or of sufficient structural order in the film. For Na and Sn alloys, however, these arguments cannot be used. No modes could be seen for such alloys even in films condensed at room temperature, heat-treated slightly, and quenched directly into liquid helium.     

Characterization of bismuth–tin–lead and bismuth–tin–lead–cadmium fusible alloys

Microstructure, electrical, mechanical and thermal properties of quenched bismuth–tin eutectic, Rose (Bi₅₀Sn_22.9Pb_27.1) and Wood’s (Bi₅₀Sn_12.5Pb₂₅Cd_12.5) alloys have been investigated using scanning electron microscopy, X-ray diffraction analysis, the double bridge method, the dynamic resonance method, Vickers hardness measurement and thermal analysis. Wood’s alloy (Bi–Pb–Sn–Cd) has low electrical resistivity and melting point but a high elastic modulus and internal friction when compared with the Rose (Bi–Pb–Sn) alloy. The presence of cadmium in Wood’s alloy decreases its melting point and electrical resistivity with an increase in its elastic modulus, which improves the mechanical properties. Wood’s alloy (Bi–Pb–Sn–Cd) has better properties, which make it useful in various applications such as in protection shields for radiotherapy, locking of mechanical devices and welding at low temperature.     

Solute-second phase interaction for Mg,Ag and Zn in Al–Li alloys

ABSTRACT

Early experiments have shown the promises of alloying with Mg?+?Ag (or Mg?+?Zn) on the performance of Al–Li alloys. To better understand the interaction between solutes and second phases in Al–Li alloys, Mg, Ag and Zn segregation to Al/δ′ interface as well as their substitution in δ′ bulk were investigated at the atomic level using first principles modelling and calculations. Energetics results and local charge analyses revealed that Mg, Ag and Zn can segregate to Al/δ′ interface by different preference, but have no significant influence on the interface adhesion. Ag and Zn can also dissolve into δ′ bulk, and enhance the local metallic bonding with nearest-neighboring Al atoms. Based on these results, a multi-fold benefit mechanism was suggested for the combined alloying with Mg?+?Ag (or Mg?+?Zn) in Al–Li alloys.     

Al-4%Ag合金中Ag原子偏析的低温正电子湮没参数研究

分别研究了823 K淬火处理和20%形变量的Al-4%Ag低温下Ag析出物对正电子的捕获行为的变化。采用正电子湮没寿命谱(PALS)技术和符合多普勒展宽能谱(CDBS)在温度范围10~293 K内对其进行表征。多普勒展宽能谱结果表明2种样品中均存在Ag析出物。正电子寿命谱的解谱结果中的各组分给出了Ag析出物随测量温度的变化规律。在170 ~273 K之间,正电子湮没行为具有较强的温度依赖性。但对于两个具有不同类型缺陷的样品,在低于170 K时观察到样品中Ag析出物捕获正电子能力出现了差异。随着测量温度的降低,淬火样品中的Ag析出物的正电子寿命和强度基本不变。在低于170 K的测量中,形变样品中的Ag析出物对正电子的捕获能力仍旧存在着较强的温度依赖性,但是变化幅度在逐渐减弱。当测量温度提升到室温(273~293 K),越来越多的正电子从Ag析出物中逃逸,逐渐回到自由状态或被其他深陷阱所捕获,失去了对温度的依赖性。     

Magnetism of surface alloys of the type MxN1−x/Rh(1 1 1)

We present a density functional theory study on the magnetic properties of two-dimensional surface alloys of the type M_xN_1−x (M=Fe, Co and Ni; N=Pt, Au, Ag, Cd and Pb) on Rh(1 1 1) for x=0.0, 0.25, 0.33, 0.5, 0.67, 0.75 and 1.0, in two types of geometric arrangements—striped phases or linear-chain type, and non-striped phases or mixed checkerboard type. Many pairs among these are bulk-immiscible but show mixing on the surface. We find that the trend in the magnetic moment of surface alloys of N with a given M follows the number of valence electrons in N: the higher the number of valence electrons, the lower the magnetic moment. Overlayer atoms when put on hcp sites show higher moment compared to fcc sites. In general, for a given composition x, linear-chain type structures show a reduced magnetic moment compared to checkerboard type structures. We find that Pb, when alloyed with magnetic elements (Fe, Co and Ni), has a lowering effect on their magnetic moments.