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.     

Temperature Dependence of Transport Properties of Liquid Sodium and Potassium

The electrical and thermal resistivities of liquid Na and K are calculated over a range of temperature at and above the melting point using the solutions of the Boltzmann equation, the form factors constructed using the Dagens-Rasolt-Taylor (DRT) model potential, the screening function of Geldart and Taylor and the X-ray structure factors of Waseda. The ratio of the electrical and the thermal resistivities is compared with the Wiedemann-Franz law and with experiment. We show that the deviation from the Lorenz number can be explained by the inelastic part of the electron-phonon scattering and the electron-electron scattering.     

Green function solution of the Boltzmann transport equation for semiconducting thin film with rough boundaries

In this study the Green function solution of the Boltzmann transport equation on semiconducting thin film with irregular walls has been applied for the first time. The effects of electron scattering caused by these irregularities on the electrical conductivity have been investigated. First of all by using coordinate transformations, the irregularities on the walls have been transferred into the volume and in this way the both surfaces have been brought into flat forms. By taking two models, Gaussian and exponential, for random potential energy term contained in the transformed Hamiltonian as the perturbation, the resistivity results have been calculated and compared with the ones obtained from the methods widely known in the literature. The Boltzmann transport equation has been solved in relaxation time approximation for the irregular walled system in the case of no magnetic field.     

Numerical Simulation of a Multi-Frequency Resistivity Logging-While-Drilling Tool Using a Highly Accurate and Adaptive Higher-Order Finite Element Method

A novel, highly efficient and accurate adaptive higher-order finite element method ($hp$-FEM) is used to simulate a multi-frequency resistivity logging-while-drilling (LWD) tool response in a borehole environment. Presented in this study are the vector expression of Maxwell's equations, three kinds of boundary conditions, stability weak formulation of Maxwell's equations, and automatic $hp$-adaptivity strategy. The new $hp$-FEM can select optimal refinement and calculation strategies based on the practical formation model and error estimation. Numerical experiments show that the new $hp$-FEM has an exponential convergence rate in terms of relative error in a user-prescribed quantity of interest against the degrees of freedom, which provides more accurate results than those obtained using the adaptive $h$-FEM. The numerical results illustrate the high efficiency and accuracy of the method at a given LWD tool structure and parameters in different physical models, which further confirm the accuracy of the results using the Hermes library (http://hpfem.org/hermes) with a multi-frequency resistivity LWD tool response in a borehole environment.     

Fabrication of cuprous and cupric oxide thin films by heat treatment

Cuprous oxide (Cu₂O) and cupric oxide (CuO) thin films were prepared by thermal oxidation of copper films coated on indium tin oxide (ITO) glass and non-alkaline glass substrates. The formation of Cu₂O and CuO was controlled by varying oxidation conditions such as, oxygen partial pressure, heat treatment temperature, and oxidation time. The microstructure, crystal direction, and optical properties of copper oxide films were measured with X-ray diffraction, atomic force microscopy, and optical spectroscopy. The results indicated that the phase-pure Cu₂O and CuO films were produced in the oxidation process. Optical transmittance and reflectance spectra of Cu₂O and CuO clearly exhibited distinct characteristics related to their phases. The electrical properties indicated that these films formed ohmic contacts with Cu and ITO electrode materials. Multilayers of Cu₂O/CuO were fabricated by choosing the oxidation sequence. The experimental results in this paper suggest that the thermal oxidation method can be employed to fabricate device quality Cu₂O and CuO films that are up to 200–300 nm thick.     

Novel powder metallurgy technique for development of Fe–P-based soft magnetic materials

Novel powder metallurgy technique (hot forging technique) is used for the development of high-density Fe–P-based soft magnetic alloys such as Fe–P binary, Fe–P–Cr ternary and Fe–P–Cr–Si quaternary alloys. In this process, mild steel encapsulated powders were hot forged into slabs, hot rolled and annealed to relieve the residual stresses. These alloys were subjected to in-house characterization, e.g. density and theoretically calculated porosity content at various stages. Microstructural study has been carried out to compare observed porosity with the theoretically calculated porosity. X-ray diffraction studies of these alloys revealed presence of only ferrite as product phase. Various soft magnetic properties such as resistivity, coercivity, maximum flux density (at 350 G magnetic field), retentivity and total magnetic losses were also evaluated and reported. These alloys were made by hot forging using two different kinds of dies, e.g. flat die and channel die. It was observed that the flat-die forged alloys had more porosity than the channel-die forged alloys. Addition of alloying elements such as P, Cr and Si increased the resistivity of Fe. The higher the alloying addition, the higher is the alloy's resistivity. Fe–0.7P–0.7Cr–1Si alloy showed a resistivity as high as 44.1 μΩ cm. Coercivity values of the alloys ranged from 1.0 to 2.2 Oe. Addition of Si and P helped in reducing the coercivity values of the alloys. The higher the Si, P content, the lower were the coercivity values observed. Combined addition of P and Si helped in reducing the coercivity values significantly, for example Fe–0.7P–0.7Cr–1Si alloy showed coercivity value approximately 1.0 Oe. It was observed in this investigation that maximum flux densities of the alloys were linearly related with their porosity levels. Total magnetic losses of these alloys varied from 6.0 to 7.8 W/kg. The total magnetic loss of Fe–0.7P–0.7Cr–1Si alloy was the lowest (6.0 W/kg) owing to its highest resistivity combined with its lowest coercivity amongst the alloys developed in the present investigation. Alloys developed in this investigation were capable of hot/cold working to very thin gage of sheet (0.5 mm thickness). These alloys could find their possible application in manufacturing of transformer core.     

Anomalous Curie-point relaxation in a Cr-containing amorphous alloy

Anomalous (negative) irreversible and reversible Curie-point relaxation was observed in amorphous Fe₇₆Cr₈B₁₅Cu₁ alloy. This observation is in line with the results previously found in a FeNiCrSiB alloy series where the Cr-concentration dependence of the normal (positive) reversible Curie-point relaxation could only be explained by assuming two contributions of different signs to the relaxation. The normal contribution is related to the ordering of Fe and Ni atoms while the anomalous one is associated with the Cr atoms. The role of Cr on the resistivity relaxation is also presented. Existing literature results on anomalous structural relaxation of metallic glasses are critically discussed.     

MULTIPLE PARAMETERS IDENTIFICATION PROBLEMS IN RESISTIVITY WELL-LOGGING

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普通电阻率测井的数值模式匹配解法

应用数值模式匹配理论计算了由任意多个轴对称多层径向不均匀介质叠加而成的地层中的普通电阻率测井响应，这种方法把二维数值问题转化为一维解析解和一维数值解的结合，因此大大减少了计算量，文中给出了反射矩阵和透射矩阵的递推公式，还提出了一种新的基函数．计算结果表明，该方法与有限元法相比具有运算效率高的优点．这种快速算法将对横向测井资料的反演在现场测井解释中应用有积极的推动作用．     

Structure and electrical resistivity of CeNiSb3

The ternary antimonide CeNiSb₃ has been prepared from an Sb flux or from reaction of Ce, NiSb, and Sb above 1123 K. It crystallizes in the orthorhombic space group Pbcm with Z=12 and lattice parameters a=12.6340(7) Å, b=6.2037(3) Å, and c=18.3698(9) Å at 193 K. Its structure consists of buckled square nets of Sb atoms and layers of highly distorted edge- and face-sharing NiSb₆ octahedra. Located between the _∞²[Sb] and _∞²[NiSb₂] layers are the Ce atoms, in monocapped square antiprismatic coordination. There is an extensive network of Sb-Sb bonding with distances varying between 3.0 and 3.4 Å. The structure is related to that of RECrSb₃ but with a different stacking of the metal-centered octahedra. Resistivity measurements reveal a shallow minimum near 25 K that is suggestive of Kondo lattice behavior, followed by a sharp decrease below 6 K.