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.     

Residual electrical resistivity of dilute nickel alloys

A quantitative calculation of the residual electrical resistivity of dilute ferromagnetic nickel-based alloys has been performed in the framework of the four-current conduction model using the kinetic equation and ab initio approaches for and ab initio approaches for the determination of the scattering potential. The contributions to the residual electrical resistivity from scattering by inhomogeneities of the impurity Coulomb potential and the exchange interaction have been separated by comparing the calculated and experimental data.     

On rigid bands and mass enhancements in noble metal alloys

The rigid band model assumes that the electronic density of states of an alloy can be inferred from that of the host. Band calculations are usually inconsistent with this model when compared with the measured electronic specific heat of alloys. It has been suggested that the apparent discrepancy for alloys with noble metal hosts is due to the neglect of changes in the electron-phonon enhancement of the density of states at the Fermi level. A semi-empirical calculation, based on measurements of the high temperature electrical resistivity, shows that changes in the enhancement factor are much too small to account for the failure of the rigid band model.     

Further experiments on energy transfer from bom barding ions to Na2O containing glasses

Abstract

The kinetics of short-range atomic ordering in austenitic Fe-17 Cr-xNi (x=10-25 wt%) alloys and in Sc-doped alloys has been studied by residual resistivity measurements during isochronal annealing in the temperature range 300-815 K. Dynamics of residual resistivity variations has shown that (i) diffusion in these alloys is observable at temperature above 700 K, (ii) preliminary cold-work deformation as well as doping by Sc atoms forms the disorder atomic structure in the austenitic matrix. It was found that Sc Atoms retard the atomic ordering process and shift it to higher temperatures. The value of temperature shift is increased from 25 to 80 K when the nickel concentration grows up to 25 wt%.     

Theory of the residual electrical resistivity of binary actinide alloys

A system of self-consistent equations has been proposed for the coherent potential approximation of the multiband conductivity model for the case of conduction electron scattering from chaotic electric fields of ions of disordered binary alloy components at zero temperature. It has been qualitatively demonstrated that the deviation of the concentration dependence of the residual electrical resistivity of actinide alloys with multiband conductivity from the Nordheim rule is caused by the explicit dependence of the electrical resistivity of the alloy on the magnitude and sign of the real part of the Green’s function at the Fermi level. The derived system of equations for the multiband coherent potential approximation has been used to calculate the concentration dependence of the density of states and the residual electrical resistivity of the alloys of neptunium and plutonium. The results of the calculations have been compared with the available experimental data.     

Electrical resistivity of liquid binary and ternary alloys

New method of calculation of the electrical resistivity of liquid and amorphous alloys is presented. The method is based on the Morgan–Howson–S̆aub (MHS̆) model but the pseudopotentials are replaced by the scattering matrix operators. The Fermi energy is properly determined by the accurate values of the phase shifts. The model depends on a very small number of universal parameters and gives stable results. The calculated values of the resistivity agree well with available experimental data for a substantial number of binary alloys. Moreover, the results for some ternary alloys were also obtained.     

Correlation between the residual resistivity and the temperature resistance minimum in amorphous alloys

A simple formula for the correlation between the residual resistivity and the temperature resistivity minimum in amorphous transition metal-metalloid alloys is derived by means of the Ziman potential scattering theory and the Kondo spin-flip scattering theory.The author would like to thank Dr.O.Hudak for helpful discussions.     

Electrical resistivity of PdHx: I. Residual resistivity

Results are presented for the electrical resistivity of PdH_x alloys at several fixed temperatures. The residual resistivity goes through a maximum at x = 0.73 and then drops sharply as x approaches 1. From this we conclude that the residual resistivity for 0.8 < x < 1 is due primarily to vacancies in the hydrogen lattice and that the hydrogen atoms occupy only the octahedral sites of the Pd lattice. The absolute values of the residual resistivity are in reasonable agreement with theoretical expectations.     

Structural relaxation and chemical decomposition in amorphous TM-M alloys

Small angle X-ray scattering experiments performed on amorphous two-component transition metal-metalloid alloys have shown that these materials decompose on annealing clearly before crystallization starts. This process influences the behaviour of physical properties in a similar way as structural relaxation does. To separate the two effects mainly composition dependent properties must be compared with others which are mainly sensitive to structural changes. In this paper it is shown that the ratio of the annealing-induced changes of the temperature coefficient of the resistivity and of the residual resistivity is determined by the underlying elementary process. The two values resulting for predominating structural relaxation and for predominating decomposition seem to be universal and are compatible with a theory of phonon-controlled conductivity in high-resistance conductors.     

Free energy and electrical resistivity of molten alloys

The free energies of mixing for molten indium-antimony, cadmium-antimony, indium-bismuth, lead-bismuth and tin-bismuth were calculated from the variation of electrical resistivity with composition employing the model of Takeuchi and Endo. Resistivities measured in this laboratory with an electrodeless technique for In-Sb alloys, together with published values for Cd-Sb, In-Bi, Pb-Bi and Sn-Bi alloys were used in the calculations.

Evaluation of the resistivity data gave the composition dependence of the derivatives of the chemical potentials of the constituents and the integral molar free energies of mixing. No assumptions regarding ideal entropy were made to obtain these free energy values although a statistically random mixture of ions is presumed in the scattering model.

Conclusions drawn from a comparison between the calculated free energy values and published thermodynamic data for these systems are discussed in terms of departures from regularity and the variations in the effective free electron concentration.     

Effect of vacancies on the resistivity of ordered alloys

An analysis is made of the effect of lattice vacancies in a binary ordered substitutional alloy with a bcc lattice on the residual resistivity. A calculation shows that the concentration dependence of the resistivity loses its symmetric form. At certain compositions vacancies can reduce the residual resistivity, and at other compositions they can increase it. An experimental study of the asymmetry of the curve will yield information about the atomic interaction energies in an alloy.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 81–87, September, 1970.     

电阻率与强度性能的关联及铜合金性能分区

铜合金以低电阻率为特征,由于电阻率与强度存在着共同的微观结构机理,两者往往协同变化,而导致难以对合金进行性能的全面评估和选材.本文以Cu-Ni-Mo合金作为研究对象,以团簇结构[Mo_1-Ni_(12)]构建固溶体的近程序结构模型,解析了电阻率和强度依赖于成分的定量变化规律,并定义了拉伸强度/电阻率的值为代表合金本质特性的"强阻比",得到了完全固溶态Cu-Ni-Mo合金的强阻比为7×10~8MPa/?·m,完全析出态的强阻比为(310—490)×10~8MPa/?·m.进而应用强阻比对常用铜合金进行了性能分区,给出铜合金材料选材的依据,得出了基于Cu-(Cr, Zr, Mg, Ag, Cd)等二元基础体系的铜合金适用于高强高导应用,而基于Cu-(Be, Ni, Sn, Fe, Zn, Ti, Al)等为基础二元体系的铜合金不能实现高强高导.该强阻比为310的特征性能分界线的发现为合金性能的全面评估提供了量化依据,可指导高强高导铜合金的选材和研发.     

Temperature and concentration dependences of the electrical resistivity for alloys of plutonium with americium under normal conditions

The temperature and concentration dependences of the electrical resistivity for alloys of americium with plutonium are analyzed in terms of the multiband conductivity model for binary disordered substitution-type alloys. For the case of high temperatures (T > Θ_D, Θ_D is the Debye temperature), a system of self-consistent equations of the coherent potential approximation has been derived for the scattering of conduction electrons by impurities and phonons without any constraints on the interaction intensity. The definitions of the shift and broadening operator for a single-electron level are used to show qualitatively and quantitatively that the pattern of the temperature dependence of the electrical resistivity for alloys is determined by the balance between the coherent and incoherent contributions to the electron-phonon scattering and that the interference conduction electron scattering mechanism can be the main cause of the negative temperature coefficient of resistivity observed in some alloys involving actinides. It is shown that the great values of the observed resistivity may be attributable to interband transitions of charge carriers and renormalization of their effective mass through strong s-d band hybridization. The concentration and temperature dependences of the resistivity for alloys of plutonium and americium calculated in terms of the derived conductivity model are compared with the available experimental data.     

Mooij rule and weak localization

It has been shown that the observed correlation between the resistivity ρ of high-resistivity metallic alloys and the sign of the temperature derivative of their resistivity can be explained by taking into account the weak localization effect. This correlation is as follows: the derivative dρ/dT is negative for alloys with resistivity in the range of 150–300 μΩ cm, which corresponds to the mean free path of electrons about the interatomic distance; however, this derivative is positive for alloys with lower resistivities (Mooij rule).     

Hall-Koeffizient und elektrischer Widerstand flüssiger Al-Ga-Legierungen

The dependence of the Hall coefficient and the electrical resistivity on temperature and concentration has been measured for liquid Al-Ga alloys. The experimental Hall coefficients were found to agree with their respective free-electron values when the assumption is made that liquid Al and Ga provide 3 free electrons per atom. The electrical resistivity versus concentration is approximately a straight line and the temperature coefficient of the electrical resistivity is always positive.     

Asymptotic region of charge density oscillation around impurities in dilute copper based alloys—II

The wipe-out number for the first order quadrupole effect in the NMR of matrix nuclei was measured in dilute Cu-Ag, Cu-Ga and Cu-Ge alloys in order to study the asymptotic behavior of the charge density oscillation around different non-transitional metal impurities. The measured values of the wipe-out numbers were compared with the predictions from Friedel's theory by using the phase shifts calculated by Blatt, Kohn-Vosko, Alfred-Van Ostenburg. “Empirical” phase shifts (η₀, η₁, η₂) for the Cu-Zn, Cu-Ga and Cu-Ge alloys were determined on the basis of Faber-Ziman diagrams. The values of the experimentally determined first order wipe-out number, the residual resistivity, and the Knight shift measured on the smelts, were described by these phase shifts.     

The ferromagnetic transition temperature of dilute Pd-Co,Pd-Fe and Pd-Mn alloys

Results of resistivity measurements on dilute Pd-Mn alloys with concentrations from 0.15 at .% to 0.7 at .% are discussed. A calculation of the transition temperature of Pd-Co, Pd-Fe and Pd-Mn alloys with concentrations between 0.05 at .% and 3 at .% is presented and compared with the available experimental data.     

Free volume dependence of the electrical resistivity of metallic glasses prepared with different quenching rates

Measurements of the electrical resistivity ρ and its temperature coefficient α have been performed on amorphous ribbons prepared with different quenching rates. The variation of ρ and α with the degree of free volume frozen in these alloys is interpreted in terms of a theory based on the Ziman approach to the resistivity of metallic glasses.     

Electrical resistivity of liquid CuGa alloys with Mn impurities

The electrical resistivity of liquid copper-gallium alloys with manganese impurities of two atomic percent has been determined by a DC-method. Compared to the pure alloys, the impurity atoms cause an increase of the resistivity which is highest for samples with no gallium. The experimental results are analyzed in the Friedel virtual bound state model.     

Effect of copper addition on some properties of rapidly solidified lead-free Sn–-10 wt% Zn alloys

This study aimed at investigating the effect of adding copper (Cu) on some properties of the lead-free alloys which rapidly solidified from melt. X-ray analysis, hardness, elastic modulus, electrical conductivity and resistivity were studied. The results indicated that the alloy hardness and elastic modulus improved by increasing the copper (Cu) content and decreasing the zinc (Zn) content. The electrical conductivity ranged from 0.250 to 0.847?×?10⁷ ohm^?1 m^?1 for the alloy under study. The electrical resistivity increases linearly with temperature until the melting point is reached. The residual resistivity results from disturbances in the lattice rather than caused by thermal vibration and the most drastic increases in the residual resistivity are caused by foreign atoms in solid solution with matrix metal. The electrical resistivity values ranged from 11.8 to 40?×?10^?8 ohm m, when the copper content changed from 0.0 to 2.0 wt% and zinc changed from 8.0 to 10.0 wt%.