Effect of short-range order on thermo-emf of binary alloys

The thermo-emf of binary disordered alloys is calculated, taking into account correlations in the distribution of atoms of different kinds over the lattice. It is shown that the presence of short-range order in the alloys may lead to a nonlinear temperature dependence of the thermo-emf and cause a change in its sign.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 87–91, November, 1976.     

The effect of ultrasonic vibrations on crystallization processes

Ultrasound has long been used during a phase transition to produce small, uniform crystals. Many theories have been suggested to explain the action of ultrasound in this application. This paper reviews the proposed mechanisms of ultrasonic crystallization.     

Vacancies in binary alloys

General expressions for the concentrations of divacancies and single vacancy-atom complexes in substitutional binary alloys is derived, using a model taking into account the interaction of neighbouring atoms as well as the interaction between vacancies and neighbouring atoms. The results of this paper are compared with those obtained with help of former theories, based on more restricted conditions.     

Thermal atomic vibrations in Cu-Ni alloys

Copper radiation has been used in an x-ray study of the temperature dependence of the effective characteristic x-ray temperature _p(T) for the alloys of the Cu-Ni system over the temperature range 293–1073 °K and in a determination of the concentration dependence of d ln_p/dT for the alloys. It is shown that _p(c) is additive. The concentration dependence of d ln_p/dT is linear. The agreement between the experimental results and data in the literature is discussed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 75–80, September, 1970.     

Effect of s-d hybridization in residual resistance of binary ordered alloys

Calculations are made of the residual resistance of the ordered binary alloys stemming from the difference between the d levels of the components. The residual resistance is found to be dependent on the degree of the long-range order. It is established that in alloys in which the Fermi energy E_F is far from the d resonances decreases monotonically as increases. When E_F approaches one of the resonance levels the resistance increases severalfold and varies monotonically with . The results are used in interpreting the anomalies of the temperature dependence of the resistance of iron-palladium alloys.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 39–44, April, 1979.The author is indebted to A. A. Kuranov and P. N. Syutkin for providing us with detailed experimental data, and to S. I. Masharov for his fruitful discussion.     

Effect of Fe addition on the crystallization behaviour and Curie temperature of CoCrSiB-based amorphous alloys

The crystallization behaviour and Curie temperature of melt-spun Co_{71? x} Fe _x Cr₇Si₈B₁₄ (x?=?0, 2, 3.2, 4, 6, 8 and 12?at.%) amorphous alloys have been studied. Differential scanning calorimetry (DSC) showed two stages of crystallization. The first stage of crystallization (T _X1) in the alloy with 6?at.%?Fe was the highest and it had the highest activation energy. X-ray diffraction studies revealed that the primary crystalline phase is hcp-(CoCr)₂Si for Fe-free alloy, whereas (CoFeCr)₂Si and (CoFeCr)₃Si phases were formed with the addition of Fe. hcp-Co was also formed along with these phases. The secondary crystalline phases were fcc-Co and various boron-rich phases. The Curie temperature of the alloys also changed with the addition of Fe to the system. Like the primary crystallization temperature, the Curie temperature of the alloys did not vary systematically with the Fe content. The addition of Fe to the Co-based system changes the nearest-neighbour interaction. This changes the exchange interaction between the transition metal elements. Due to the asymmetry in the Bethe–Slater curve, a systematic variation with Fe addition was not observed in the Curie temperature measurement.     

Mixing in binary liquid alloys

A review of some experimental results and theories of mixing in binary metallic systems indicating properties of the constituents of importance and ways in which the existing theories may be adapted to describe some of the results.     

Optical modes in binary alloys

The existence of a high-frequency, long-wavelength mode in a binary alloy is discussed on the basis of the fourth frequency moment of the correlation between concentration fluctuations.     

Anisotropic ordering in binary alloys

The problem of ordering in a binary alloy with anisotropic interaction between atoms is analyzed in the Kirkwood approximation. It is shown that the emerging oriented superstructure does not depend on the isotropic component of ordering energy. Transition to the ordered state destroys the short-range anisotropy. The constant of induced magnetic anisotropy is calculated for a ferromagnetic alloy, while its dependence on the alloy composition and the degree of far-range order as well as on the anneal temperature and the test temperature is established.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 109–112, March, 1976.     

Electromigration in non-dilute binary alloys

This paper comments the recently published works on the electromigration in non-dilute binary alloys and gives a general analysis for calculating the effective valences $\text{Z}{}_{\mathrm{i}}{}^1$ of both components from experimental measurements. The proposed expressions for $\text{Z}{}_{\mathrm{i}}{}^1$ can be reduced to simple forms when Manning's expressions [5] for the phenomenological coefficients are used. These results allow us to calculate the effective valences of Silver and Gold in non-dilute Ag-Au alloys from Hofman and Guy's experimental data.     

Ordering in binary FCC alloys

A new method of approximation for studying the order-disorder transition in binary alloys is presented. The formulation is in terms of face-centered cubic alloys, although the method can also be applied to other structures. The technique is essentially a generalization of the constant-coupling approximation. We have applied the principles of that method to derive the free energy of the alloy using a tetrahedral cluster of nearest neighbouring sites as the basic unit of the calculation. We only consider the case of nearest neighbour pair interactions, but show how the method can be generalized to include many body and second neighbour interactions. Numerical results are presented and comparison of these results is made with results of cluster variation calculations on the same system and with experimental results on the copper-gold alloy system.     

Lattice dynamics of some binary alloys

Summary The phonon dispersion frequencies for Cu₃Au, Cu₃Zn and Ni₃Fe alloys have been calculated using the model potential approach. The contribution of a short-range three-body interaction to the dynamical matrix has also been included in the present study. The theoretically computed phonon dispersion curves of these alloys are found to be in good agreement with the experimental data.     

Effect of the composition of binary alloys melted in contact with tin on its plasticity

The effect of the composition of binary Bi-, Cd-, In-, and Pb-base alloys on the plasticity of tin has been investigated at various temperatures under conditions of contact melting with the alloys. The adsorption activity of the melt formed as a result of the contact melting was dependent on its composition, the later being determined not only by the ratio of the active and inactive components in the solid alloys, but also by the temperature of the experiment.     

Superconducting state parameters of binary alloys

The theoretical investigation of the superconducting state parameters (SSP) viz. electron–phonon coupling strength $\lambda$, Coulomb pseudopotential μ^*, transition temperature T_C, isotope effect exponent α and effective interaction strength N_OV of large numbers of binary alloys have been made extensively in the present work using a model potential formalism for the first time with pseudo-atom-alloy (PAA) model. A considerable influence of various exchange and correlation functions on $\lambda$ and μ^* is found from the present study. The present results of the SSP are found in qualitative agreement with the available experimental data wherever exist.     

Behaviour of positrons in binary alloys

The pseudopotential picture of the positron in a binary alloy is developed. It is shown that the positron is usually preferentially attracted to one sort of atom in the alloy. This relative positron affinity is associated with the positron pseudopotential difference between the different sorts of atom and calculations of this quantity are presented for a number of 50 at % alloys.     

Inherent submicroporosity and crystallization of amorphous alloys

The effect of inherent submicroporosity (regions with an excess free volume) in amorphous alloys on the regularities of their crystallization is investigated. Inherent submicroporosity arises in amorphous alloys prepared by quenching under different conditions. It is proved that this effect should be taken into account in the first stage of crystallization of amorphous alloys.