Ordering diagrams for ternary alloysA-B-(C) with an fcc lattice

The pattern of atomic ordering in ternary alloys A-B-(C) with an fcc lattice and L1₂ superstructure, in which the atoms of the component C occupy octahedral interstices, was investigated. The possible ordering diagrams of these systems were determined.Ural Polytechnical Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 42–46, December, 1993.     

The theory of atomic and magnetic ordering in ternary alloys with fcc lattice

We consider the theory of the mutual influence of atomic and spin ordering phenomena in ternary alloys of transition elements with fcc lattice. The case of quasibinary alloys B₃A-B₃D is considered in detail. Concentration dependences of the critical temperature of the order-disorder phase transition are considered for cases of atomic and magnetic ordering.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 48–57, December, 1970.     

Ordering of ternary alloys in the self-consistent field approximation

In the self-consistent field approximation, without allowance for correlation, a static theory of the ordering of ternary alloys is constructed which makes it possible to take into account the long-range nature of the interatomic interaction forces in substitutional and interstitial alloys. The theory enables one to take into account the possible existence in the alloy of two subsets of points differing by the species of atoms that occupy them. The stability of the disordered state in such alloys is analyzed and an expression obtained for the temperature at which the disordered state loses stability.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 61–64, November, 1980.     

Theory of adsorption at antiphase boundaries in ternary fcc ordered alloys

The adsorption of alloying elements at (111) antiphase boundaries (APB's) in ternary fcc ordered alloys is analyzed. The atomic segregation at the APB's and the long-range order parameters at the APB's and within domains are studied as functions of the temperature and the concentration of alloying elements. The results are compared with experimental data for ternary bcc alloys.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 2, pp. 96–104, February, 1971.     

Local vibrations in fcc crystals with two-parametric substitutional impurities

The threshold parameters of defects (the mass defect and the relative change in the force constants) are determined at which local vibrations start to occur in an fcc crystal with substitutional impurities. The characteristics of local vibrations are investigated, and the influence of the defect parameters on the frequency of local vibrations and their decay rate with distance from the impurity atom is analyzed. The frequencies and the intensities of local vibrations are calculated for the nearest neighboring atoms of an impurity, which, combined with the impurity atom, form a defect cluster.     

Ordering of body-centered cubic ternary alloys with three types of site. I

The ordering theory of A-B-D alloys with body-centered cubic (bcc) lattices and three types of site is examined by the Gorskii-Bragg-Williams approximation. It is shown that under certain conditions there can be two critical temperatures (T₀) for the order-disorder phase transition. The case of alloys with a quasi-binary BA-BD section is examined in detail.     

Pseudopotential study of lattice parameter and heat of formation for substitutional alloys

Ashcroft’s empty core pseudopotential is applied to the substitutional alloy (K-CS) to calculate the heat of formation and lattice parameter over the entire concentration range. At any concentration the defect crystal is considered to be equivalent to a perfect crystal with a modified lattice parameter and the potential parameter for the defect crystal is calculated by using some suitable interpolation formula. The calculated results agree well with the available experimental results.     

Recrystallization of selected metals and alloys with fcc lattice after high speed hot forming

In 1966 when studying the recrystallization of austenite after high speed hot forming, Pluha and Zuna observed a phenomenon which consisted in the nucleation and new grain growth right in the recrystallized matrix, following a pronounced grain coarsening. The phenomenon was called the second recrystallization. On the basis of the present-day knowledge the second recrystallization can be considered as a specific case of metadynamic or static recrystallization. Its characteristic feature — grain coarsening before refining — offers an analogy with the recrystallization after small deformations.     

Temperature dependence,at low temperatures,of macroscopic elastic limit of polycrystals of substitutional solid solutions with fcc lattice

The influence of temperature within the range of 77–293°K on the macroscopic elastic limit σ″ of polycrystals of solid solutions Cu-Ni and Cu-Al was studied. The ratio of the macroscopic elastic limit of the polycrystals was obtained. The contribution of various factors to σ″ and its temperature dependence was analyzed. It was demonstrated that the latter is determined by the temperature dependence of the interaction of dislocations with atoms of the alloying element.     

Theory of the existence of a two-phase region in ternary ordered fcc alloys

The limiting temperatures of the two-phase region in ternary ordered fcc alloys of the quasibinary B₃A-B₃D system are found on the basis of equality of the chemical potentials of the components of the ordered and disordered phases (in the Gorskii-Bragg-William approximation). The effect of the relative magnitudes of the three ordering energies on the nature of the phase diagrams of the ternary ordered alloy is analyzed.Translated from Izvestiya VUZ. Fizika, No. 7, pp. 54–60, July, 1970.     

Ordering processes and activation energy in Ni3Fe-based ternary alloys

The measurement of electrical resistance () has been used, to study the kinetics of isothermal ordering in the range 200 °–545 ° C in Ni₃(FeMn) alloy quenched from 970 ° C, and the kinetics of ordering at 390 ° C in the alloy quenched from various temperatures in the 600 °–800 ° C range. The sections method and the gradient of the (t) curves were used to find the activation energy for migration and vacancy formation in this alloy on the assumption that the excess vacancies frozen in the alloy by quenching at temperatures above T_c are responsible for ordering. The activation energies for vacancy formation and migration were respectively U₀ = 33 ± 3 kilocal/mole and U_m = 39 ± 4 kilocal/mole, which in total give the activation energy for diffusion Q = 72 ± 7 kilocal/mole in the alloy studied; this approximates to the activation energy for diffusion in pure nickel.     

Band structure and lattice vibration properties of III-P ternary alloys

Electronic band structure, optical and vibrational properties of zinc-blende GaP_xSb_1−x and GaAs_1−xP_x ternary alloys are obtained from pseudo-potential calculations. Comparisons are made with the available experimental values and with data obtained in previous theoretical studies. These comparisons show generally good agreement between the present results and experiment. The direct and indirect band-gap energies, the transverse effective charge, and the longitudinal and transversal optical phonon energies show a non-linear behavior with varying the composition x. The ionicity of the materials of interest is discussed in terms of the antisymmetric gap.     

Interaction between interstitial hydrogen and substitutional solute atoms in solid solutions of niobium-base ternary alloys

The interaction between interstitial hydrogen and substitutional solute atoms has been investigated by the measurements of the hydrogen solubility and the influence of hydrogen charging on the half-width of the X-ray reflection lines in pure Nb, Nb-5%V, Nb-5%Mo and Nb-5%Ta alloys. In Nb-5%V and Nb-5%Mo alloys, the solubility considerably increases with respect to pure Nb. On the other hand, the solubility hardly changes in Nb-5%Ta alloy. With addition of hydrogen, the half-widths in pure Nb and Nb-5%Ta alloy show a monotonic increase, but in Nb-5%V and Nb-5%Mo alloys they show a minimum. The results are explained by the interaction of hydrogen with substitutional solute atoms. The interaction is considered to be caused by the internal strain induced by the difference in atomic radii between substitutional and solvent (Nb) atoms.     

Temperature characteristic of anisotropy with respect to mechanical strength in crystals with an fcc lattice

This study concerns the temperature characteristic of anisotropy with respect to mechanical strength in an fcc crystal lattice with centripetal pairwise interaction between atoms, under stresses which preserve the tetragonal lattice symmetry and under shearing stresses which preserve the orthorhombic symmetry. The study also deals with the problem of how the nature of the bond forces affects this anisotropy.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 42–45, June, 1976.     

Ordering in alloys

Abstract

The continuous ordering process can be viewed as a development and a gradual amplification of concentration modulations with wave lengths of the order of a few lattice spacings. How the development of different concentration modulaltions leads to different superlattice structures in cubic systems is explained with the help of some illustrative examples. The importance of concentration modulations with special point wave vectors in the stability of the various coherent superlattice structures is discussed. Experimental evidences for such continuous ordering is cited from recent results on ordering in Ni-Mo alloys.

The evolution of ordering in some systems can also be viewed as progressively tiling the disordered lattice by superlattice tiles. When more than one type of coherent superlattice tiles compete, juxtaposition of different types of tiles can occur during the course of ordering. The transitional states between the short range and the long range ordered Ni-Mo alloys indeed exhibit such structures where different types of superlattice tiles decorate the fcc lattice. The role of special point concentration waves in the development of such structures will be discussed in relation to the secondary ordering processes involving two perpendicular ?1 ½ 0? waves and a combination of an ?1 ½ 0? and an appropriate ?100? wave.     

Theory of ordering of ternary substitutional solid solutions

The theory of the ordering of ternary substitutional solid solutions of the type B(A_m–D_n) with body-centered (bcc) cubic lattices and the type B₃(A_m–D_n) with face-centered cubic lattices (fcc) is investigated by the Gorskii-Bragg-Williams method. The applicability of the results obtained is analyzed.     

Local environment effect in substitutional alloys

The local environment effect in substitutional alloys is considered. We calculate the local density of states by adding a local scattering correction to the average Green's function of the single-site coherent-potential approximation. Our numerical results indicate the importance of a local environment to the local electronic structures.