Impurity effect of Me=Cr,Nb or Mn third component atoms on hyperfine interactions in ordered Ni3Fe alloy

Investigations of atomic ordering in Ni₃Fe, Ni₃(Fe, Nb), Ni₃(Fe,Cr) and Ni₃(Fe, Mn) alloys at room temperature in disordered and ordered states have been carried out by Mössbauer spectroscopy method. The experimental results confirm that in case of Ni₃Fe superstructure stabilization is achieved by Nb and Mn atoms, the Cr atoms disturb this structure.     

Hall effect in the ternary ordered alloys Ni3(Mn,Fe) and Ni3(Mn,Co) II. Ordered solid solutions

An experimental study was made of the changes in the normal and anomalous Hall constants R₀ and R_s, respectively, the internal saturation induction B_s, and the resistivity ? during the ordering of quasibinary Ni₃Mn-Ni₃Fe and Ni₃Mn-Ni₃Co alloys. The concentration dependences of R₀, R_s, B_s, and ? were also studied in the ordered state of these alloys. It is concluded from an analysis of the experimental results that the decreases inR₀ and ? during the ordering of Ni₃Mn and as a result of the alloying of ordered Ni₃Mn with slight amounts (～5 at. %) of iron are due primarily to a decrease in the hole contribution to transport and to a decrease in the state density in the 3d band of these alloys near the Fermi level. The experimental data are in satisfactory agreement with the curve calculated by Yamashita et al. [6] for the density of 3d states in ordered Ni₃Mn and Ni₃Fe alloys.     

Change in strain hardening and elastic properties during isothermal ordering of alloys based on Ni3Fe

A study has been made of the change in the Young's modulus, yield point, hardness, hardening coefficient, slip pattern, and duration of the linear stage in the flow curves during the isothermal ordering of the polycrystalline alloys Ni₃Fe, Ni₃(Fe + 2% Al), Ni₃(Fe + 3% Mn), and Ni₃(Fe + 2.5% Cr). A definite relationship has been observed between the changes in these properties at the various stages of ordering.     

Monte Carlo investigation of the correlation between magnetic and chemical ordering in NiFe alloys

The Ni_xFe_1−x alloys close to the stoichiometric Ni₃Fe composition are modeled by means of Monte Carlo simulations. To describe the atomic and magnetic configurations, the Ising and Heisenberg models with nearest-neighbor interactions have been used, respectively. The pairwise interactions have been fitted to the experimentally measured Curie and Kurnakov temperatures, the Fe-Fe magnetic exchange interaction has been considered antiferromagnetic. The mutual influence of the magnetic and chemical ordering is evidenced and a good agreement with the phase diagram is obtained. Our numerical results show that the magnetic order is able to increase the Kurnakov temperature and, reciprocally, the chemical order is responsible for a rise in the Curie temperature. Also, the influence of the applied magnetic field on the chemical order is investigated and an increase of the Kurnakov temperature with the external field is observed.     

Magnetic behavior of amorphous Fe−Ni−Zr alloys and their response to radiation damage

The magnetic properties of two amorphous Fe?Ni?Zr alloys, Fe_89.7Ni_0.03Zr₁₀ and Fe₇₀Ni₂₀Zr₁₀, both in the “as cast” and neutron irradiated states were investigated by Mössbauer spectroscopy and dc magnetic susceptibility measurements. The upper magnetic ordering temperatures of Fe_89.7Ni_0.03Zr₁₀ are 232K and 246K for the “as cast” and irradiated samples, respectively. The magnetic ordering temperature for Fe₇₀Ni₂₀Zr₁₀ was about 478K for both the “as cast” and irradiated samples. Both compositions yield magnetic hyperfine spectra, which show a considerable relaxation effect that must be explicitly considered in the calculation of the average local Fe moments. When this is done, these values derived from Mössbauer spectra are in good agreement with the dc susceptibility values. The effects of neutron irradiation on the magnetic properties of these alloys are small.     

Atomic configuration of microtwins in alloys having Ll2 superstructure

In the approximation of paired interatomic potentials of the Morse type, modeling is done on the atomic configuration and energy of formation of superstructure stacking faults and superstructure twinning stacking faults in the ordered alloys Cu₃Au and Ni₃Fe, and also in the intermetallide Ni₃Al. Features are observed in the local deformation of the crystal lattice defects near equilibrium (in terms of internal energy), and the principle difference in the state of the atomic surroundings of the examined plane defects is shown. In alloys of Cu₃Au and Ni₃Fe, calculations are done for different values of the long-range order parameter. A difference is detected in the variation of the energy of formation of superstructure twinning stacking faults in alloys of Cu₃Au and Ni₃Fe with the long-range order parameter. This difference correlates with experimental observation of the properties when varying the temperature in the alloys.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 31–36, November, 1987.     

Effect on alloying at the Fe/Ni(001) interfaces on the interlayer exchange coupling

We investigate the stability of various ordered FeNi alloys at the interfaces of Fe/Ni superlattices by using ab initio density functional calculation. We consider an Fe_0.5Ni_0.5 ordered alloy of one or two monolayers thick at different positions beyond the interface and the possibility of an interdiffusion of a complete monolayer of Ni(Fe) in Fe(Ni) slab. An interfacial atomic layer of Fe_0.5Ni_0.5 exchanged with its adjacent Ni monolayers, leading to a buffer zone of Ni₃Fe composition is found to be the most stable structural configuration. For this atomic arrangement we investigate the magnetic profile and the resulting interlayer exchange coupling between the Ni slabs for Fe spacer thickness of 0 to 4 monolayers.     

High-temperature site preference and atomic short-range ordering characteristics of ternary alloying elements in γ’-Ni3Al intermetallics

Abstract

Remarkable high-temperature mechanical properties of nickel-based superalloys are correlated with the arrangement of ternary alloying elements in L1₂-type-ordered γ′-Ni₃Al intermetallics. In the current study, therefore, high-temperature site occupancy preference and energetic-structural characteristics of atomic short-range ordering (SRO) of ternary alloying X elements (X = Mo, W, Ta, Hf, Re, Ru, Pt or Co) in Ni₇₅Al_21.875X_3.125 alloy systems have been studied by combining the statistico-thermodynamical theory of ordering and electronic theory of alloys in the pseudopotential approximation. Temperature dependence of site occupancy tendencies of alloying X element atoms has been predicted by calculating partial ordering energies and SRO parameters of Ni-Al, Ni-X and Al-X atomic pairs. It is shown that, all ternary alloying element atoms (except Pt) tend to occupy Al, whereas Pt atoms prefer to substitute for Ni sub-lattice sites of Ni₃Al intermetallics. However, in contrast to other X elements, sub-lattice site occupancy characteristics of Re atoms appear to be both temperature- and composition-dependent. Theoretical calculations reveal that site occupancy preference of Re atoms switches from Al to both Ni and Al sites at critical temperatures, T_c, for Re > 2.35 at%. Distribution of Re atoms at both Ni and Al sub-lattice sites above T_c may lead to localised supersaturation of the parent Ni₃Al phase and makes possible the formation of topologically close-packed (TCP) phases. The results of the current theoretical and simulation study are consistent with other theoretical and experimental investigations published in the literature.     

Calculation of the structure of the 4s band for Ni3Mn and Ni3Fe ordered alloys

Perturbation theory has been applied to the structure of the 4s band of Ni₃Mn and Ni₃Fe ordered alloys; the Fermi surfaces have been constructed for these alloys in the one-wave approximation, and the electron state densities and electron energy change on ordering have been calculated. It is found that the contribution of the 4s electrons to the ordering energy is much less than that of the 3d electrons.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 102–106, July, 1972.     

Some regularities of the fracture of ordered alloys based on Ni3Fe

Some regularities of the fracture of ordered polycrystals of the alloys Ni₃Fe, Ni₃(FeMn), Ni₃FeAl), Ni₃(FeCr), Ni₃(FeCr) are studied. The alloys Ni₃Fe, Ni₃(FeMn), and Ni₃(FeAl) possess low plasticity in the ordered state at the test temperatures T < 100 °C. In the 100–200 ° C temperature range a brittleness-viscosity transition is detected which is analogous to that observed in body centered cubic (BCC) metals and alloys. The transition from the brittle into the plastic state is not accompanied by a change in the metallographic picture of slip. The distinguishing peculiarity of the strain at elevated temperatures is the significant displacement of the grains along the boundaries. The temperature band of the transition from the brittle into the plastic state of ordered alloys in the tempered state (tempering from a temperature below the temperature of the order-disorder transformation) is observed at tempering temperatures above 450 °C (tests at room temperature). The results obtained permit the assumption that a reduction in the plasticity in ordering alloys based on Ni₃Fe is caused by segregation of the impurities along the grain boundaries.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 6, pp. 35–41, June, 1971.     

Hall effect in the ternary ordered alloys Ni3(Mn,Fe) and Ni3(Mn,Co) 1. Disordered solution solutions

The normal and anomalous Hall constants R₀ and R_s, respectively, and the resistivity have been measured for the quasibinary alloys Ni₃Mn-Ni₃Fe and Ni₃Mn-Ni₃Co. The results imply that in ternary alloys of Ni₃Mn containing slight Fe and Co impurities the hole regions of the Fermi surface make an important contribution to R₀ and that the primary scattering mechanism for the carriers corresponding to the anomalous Hall current in the alloys with Fe at room temperature is phonon scattering. It is concluded that the Fermi surface of the Ni₃Mn-Ni₃Fe alloys is closed.Translated from Izvestiya VUZ. Fizika, No. 3, pp. 21–29, March, 1970.     

Quantitative calculations of thermal-expansion coefficient in Fe–Ni alloys: First-principles approach

The thermal expansion coefficients (α) of Fe_1-xNi_x alloys are calculated by means of the Debye-Grüneisen model, which uses the input parameters calculated from density functional theory (DFT) with collinear spin alignments. The various atomic configurations of fcc and bcc supercells with x being 0–0.5 are calculated to conduct the composition-specific analysis. Thermodynamic analysis is employed to facilitate the evaluation of α in bulk alloys, where the calculated supercells are used as the canonical ensemble. Such calculated α exhibits very similar composition-dependency in comparison with the experimental data from literature, particularly providing the well-known Invar effect at 65 wt% of Fe. The calculations also demonstrated that the pressure-derived magnetic frustration, i.e. the magneto-volume effect, is strongly correlated with the Invar effect. The present approach combining the Debye-Grüneisen formalism and the collinear DFT calculation is shown to be a comprehensive theoretical framework for analysis on the thermal expansion properties in metal alloys.     

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.     

Antiferromagnetism of the α-Mn system

The variation of the Néel temperature (T_N) of antiferromagnetic alloys of Mn with 3-d elements has been studied by electrical resistivity measurements. Binary Mn-rich alloys Fe, Co, Ni, Ti, Rh, Os, Ir, and Ru were investigated. The results show a strong and systematic dependence on the number of d-electrons of the impurity element. Elements with more d electrons than Mn raise T_N, while those with fewer d electrons depress T_N. The change of T_N per atomic percent impurity also exhibits a striking, non-monotonic dependence on the impurity used. The dependence shows inversion symmetry with impurities around Mn.To further elucidate the properties of the Mn-rich antiferromagnetic system, a study was made of ternary Mn-rich alloys in the MnFeCr, MnCoNi, and MnVTi systems. The results from the MnFeCr system are consistent with the rigid-band model, the average number of d-electrons per atom being of primary importance determiningh the antiferromagnetism in this system.Our goal in these studies has been to provide a firm experimental data baseupon which future theoretical work can be built. A more detailed understanding of the very intriguing α-Mn magnetic system now awaits further theoretical investigation.     

Acceleration of ordering in iron-, cobalt-, and chromium-doped Ni3Mn

The various factors which can affect ordering in alloys are analyzed. The results of the analysis are applied to the ordering in Ni₃(Mn, Me) (Me = Fe, Co, or Cr) alloys. It is concluded that the accelerated ordering in these cases is caused by a change in the ordering mechanism from a homogeneous mechanism in Ni₃Mn to a heterogeneous mechanism in the ternary alloys and by an increase in the vacancy concentration due to doping.Translated from Izvestiya Vysshikh Uchebnykh Zavadenii Fizika, No. 1, pp. 73–78, January, 1970.     

Hall effect in dilute magnetic alloys

We review the theory and the experimental results on the Hall effect in noble metals containing magnetic impurities of transition metals. In order to illustrate the various types of observed effects, we focus succesively on selected systems: $\text{Cu}$Mn, with only enhancement of the ordinary Hall effect due to the existance of different spin-up and spin-down currents; $\text{Au}$Fe and $\text{Au}$Cr, with skew scattering by magnetic impurities; $\text{Cu}$MnT ternary alloys (where T is a non-magnetic impurity), with skew scattering effects due to combined spin—orbit scattering by non-magnetic impurities and spin scattering by Mn impurities. The skew scattering in $\text{Au}$Fe and $\text{Au}$Cr can be ascribed to the orbital character of the impurity moments and accounted for in an orbitally degenerate virtual bound state model. However, the anomalous temperature dependence of the skew scattering in Kondo alloys at low temperature is not well understood. We also present some magnetoresistance data in order to describe the links between the Hall effect and the magnetoresistance in magnetic alloys. In particular, we relate the skew scattering and the magnetoresistance anisotropy observed in $\text{Au}$Cr alloys.     

Investigation of electrical resistivity and average magnetic moment per atom of Ni3(Fe,Ti) and Ni3(Mn,Ti) alloys

The electrical resistivity and average magnetic moment per atom of Ni₃(Fe, Ti) and Ni₃(Mn, Ti) alloys were measured. X-ray structural analysis revealed the presence of the Ni₃Ti phase in Ni₃(Fe+7% Ti) and Ni₃(Fe + 10.3% Ti), and strong interaction of Ni and Ti is deduced. The introduction of Ti into Ni₃Mn reduces the antiferromagnetic Mn-Mn interaction and thus leads to greater ordering.Deceased.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 9–12, May, 1981.     

Certain features of the electronic structure of ternary alloys of Ni3Mn with iron and cobalt

Features of the electronic structure of ternary alloys of the quasibinary Ni₃Mn-Ni₃Fe and Ni₃Mn-Ni₃Co systems are discussed on the basis of an analysis of the changes in the absolute thermal emf S and in the conductivity . It is concluded that all the ternary Ni₃Mn-Ni₃Fe alloys have a closed Fermi surface in both the disordered and ordered states. It is confirmed experimentally that a deep minimum appears on the state-density curve N_d(E) during the ordering of Ni₃Mn-Ni₃Fe alloys, and the alloy composition whose Fermi surface corresponds to this minimum is given.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 8, pp. 126–133, August, 1969.     

Effect of Fe substitution on the phase stability and magnetic properties of Mn-rich Ni-Mn-Ga ferromagnetic shape memory alloys

The influence of Fe additions on the martensitic transformation and magnetic properties of Mn-rich Ni-Mn-Ga alloys was investigated by substituting either 1 at% Fe for each atomic species or by substituting Ni with varying amounts of Fe. The magnetic structure of the alloys was studied using ⁵⁷Fe Mössbauer spectroscopy. Mössbauer spectra revealed typical paramagnetic features in Mn-rich Ni-Mn-Ga-Fe alloys owing to the preferential site occupancy of Fe atoms at Ni sites. The evolution of the magnetic properties and phase stability has been correlated with the chemical and atomic ordering in these alloys.