Strain field due to transition metal impurities in Ni and Pd

The strain field due to body centered substitutional transition metal impurities in Ni and Pd metals are investigated. The calculations are carried out in the discrete lattice model of the metal using Kanzaki lattice static method. The effective ion-ion interaction potential due to Wills and Harrison is used to evaluate dynamical matrix and the impurity-induced forces. The results for atomic displacements due to 3d, 4d and 5d impurities (Fe, Co, Cu, Nb, Mo, Pd, Pt and Au) in Ni and (Fe, Co, Cu, Ni, Nb, Mo, Pt and Au) impurities in Pd are given up to 25 NN’s of impurity and these are compared with the available experimental data. The maximum displacements of 4.6% and 3.8% of 1NN distance are found for NiNb and PdNb alloys respectively, while the minimum displacements of 0.63% and 0.23% of 1NN distance are found for NiFe and PdFe alloys respectively. Except for Cu, the atomic displacements are found to be proportional to the core radii and d state radius. The relaxation energies for 3d impurities are found less than those for 4d and 5d impurities in Ni and Pd metals. Therefore, 3d impurities may easily be solvable in these metals.     

Investigation of the degree of occupancy of 3d and 4s bands of 3d metals and their alloys on the basis of a four-band model

A four-band model is used as the basis for obtaining relationships suitable for the calculation of a number of the s electrons in 3d metals and their alloys. The results are given of calculations of this number in Fe, Co, Ni, and Cu, and their Fe-Co, Co-Ni, and Ni-Cu alloys. A quantitative agreement is found between the number of the s electrons and the available published data. The results indicate the presence of vacant states in the d band of Cu and in the d subband of Ni, which is usually assumed to be completely filled. The results demonstrate shortcomings of the four-band model in explaining the magnitude of the normal Hall coefficient of Co and of Fe-Co, Co-Ni, and Ni-Cu alloys.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 71–77, May, 1980.     

Magnetic contribution to the atomic volume of Co,Fe, Mn and Fe-3d metal alloys

The atomic volumes of the polymorphic 3d elements Mn, Fe and Co, and the average atomic volumes of alloys of Fe with Ni, Co, Mn, Cr and V are examined using a simple magnetovolume relation presented previously. The variation of the atomic volumes of the elements and of the alloys is shown to follow the variations in the magnetic moments associated with the atom through this relation.     

Magnetic contribution to the atomic volume of d group transition metals

A simple relation is presented to describe the dependence of the volume of a d group metal atom on its magnetic moment using a single constant independent of the atom involved, the crystal structure, atomic enviroment, type and strength of magnetic order. This relation is extended to binary alloys and its significance in special cases discussed. The validity of this relation is checked for a wide range of Fe, Mn and Cr binary alloy systems in subsequent papers.     

Atomic displacements in bcc dilute alloys

We present here a systematic investigation of the atomic displacements in bcc transition metal (TM) dilute alloys. We have calculated the atomic displacements in bcc (V, Cr, Fe, Nb, Mo, Ta and W) transition metals (TMs) due to 3d, 4d and 5d TMs at the substitutional site using the Kanzaki lattice static method. Wills and Harrison interatomic potential is used to calculate the atomic force constants, the dynamical matrix and the impurity-induced forces. We have thoroughly investigated the atomic displacements using impurities from 3d, 4d and 5d series in the same host metal and the same impurity in different hosts. We have observed a systematic pattern in the atomic displacements for Cr-, Fe-, Nb-, Mo-, Ta-and W-based dilute alloys. The atomic displacements are found to increase with increase in the number of d electrons for all alloys considered except for V dilute alloys. The 3d impurities are found to be more easily dissolved in the 3d host metals than 4d or 5d TMs whereas 4d and 5d impurities show more solubility in 4d and 5d TMs. In general, the relaxation energy calculation suggests that impurities may be easily solvable in 5d TM hosts when compared to 3d or 4d TMs.      

Die magnetische Suszeptibilität flüssiger Übergangsmetallegierungen

Investigations on the magnetic susceptibility of alloys of the transition metals Fe, Co and Ni with the normal metals Au, (Cu), Zn, Ga and Ge were performed in the liquid state over the whole concentration range. These alloys show complicated phase diagrams, so that in the solid state a systematic investigation over the whole concentration range is not possible. The results are discussed with the existing models for the transition metal rich side and for impurities of transition metal in normal metals. A connection between the susceptibility and the density of states has been found, which allows to explain the behaviour of the susceptibility over the whole concentration range. The measurements of the susceptibility give some information about shape and position of the density of states on alloying.     

非晶态铁磁Fe-Ni基合金的穆斯堡尔谱研究

本文研究了非晶态合金Fe_81-xNi_xSi_3.5B_13.5C₂(x=5,10,15,20,25,30,35)及坡莫合金Fe₅₀Ni₅₀在室温和外加磁场下的穆斯堡尔谱,用拟谱方法获得了超精细相互作用的参量及超精细场分布P(H).实验结果表明,非晶态Fe-Ni基合金存在两种磁性铁原子且有类因瓦特性,在x=15左右存在异常现象.文中提出了外加磁场和低温的外界条 关键词：     

Density functional theory study of structural,electronic,and thermal properties of Pt,Pd, Rh,Ir, Os and PtPdX(X= Ir,Os, and Rh) alloys

The structural, electronic, mechanical, and thermal properties of Pt, Pd, Rh, Ir, Os metals and their alloys Pt Pd X(X= Ir, Os and Rh) are studied systematically using ab initio density functional theory. The groundstate properties such as lattice constant and bulk modulus are calculated to find the equilibrium atomic position for stable alloys. The electronic band structure and density of states are calculated to study the electronic behavior of metals on making their alloys. The electronic properties substantiate the metallic behavior for all studied materials. The firstprinciples density functional perturbation theory as implemented in quasi-harmonic approximation is used for the calculations of thermal properties.We have calculated the thermal properties such as the Debye temperature, vibrational energy, entropy and constant-volume specific heat. The calculated properties are compared with the previously reported experimental and theoretical data for metals and are found to be in good agreement. Calculated results for alloys could not be compared because there is no data available in the literature with such alloy composition.     

合金化成分对NiTi合金M_s点影响的正电子湮没研究

用双探头符合系统测量了金属Fe、Co、Ni、Al、Nb、Cu、Ti和NiTi合金的多普勒展宽谱,计算了其S参数和W参数,分析了合金中d-d金属键的作用.结果表明,当用Fe、Co或Al原子加入NiTi合金时,都将使合金中参与形成d-d金属键的d电子减少,从而使金属键减弱;而用Cu或Nb原子加入NiTi合金时,对合金中d-d电子作用的影响很小,合金中共价键的成分变化不大.在NiTi合金中加入合金化元素可以改变其电子结构,进而影响Ms点.     

A simple analytical EAM model for bcc metals including Cr and its application

An analytical embedded atom method (EAM) model, which can treat bcc transition metal Chromium, has been developed. In this model, a new potential was presented, and a modified term has been introduced to fit the negative Cauchy pressure P _c=(C₁₂-C₄₄)/2 for element Cr. The new model was applied to calculating the thermodynamic properties of binary alloys of all bcc transition metals V, Nb, Ta, Cr, Mo, W and Fe. The calculated dilute-solution enthalpies and formation enthalpies of random alloys are in good agreement with the experimental data available, the results from the first-principles calculations, and the results of thermodynamic calculations.     

Ab initio calculation of the Gilbert damping parameter via the linear response formalism

A Kubo-Greenwood-like equation for the Gilbert damping parameter α is presented that is based on the linear response formalism. Its implementation using the fully relativistic Korringa-Kohn-Rostoker band structure method in combination with coherent potential approximation alloy theory allows it to be applied to a wide range of situations. This is demonstrated with results obtained for the bcc alloy system Fe(1-x)Co(x) as well as for a series of alloys of Permalloy with 5d transition metals. To account for the thermal displacements of atoms as a scattering mechanism, an alloy-analogy model is introduced. The corresponding calculations for Ni correctly describe the rapid change of α when small amounts of substitutional Cu are introduced.     

Calculation of the structural characteristics of liquid alloys with strong component interaction

The short-range order parameters and atomic interaction energies are used in expressions for the pore concentration and mean coordination number within the first coordination sphere for liquid binary alloys. The mean interatomic distances have been calculated from measurements on the density (molar volume). Structural characteristics have been calculated for the liquid suicides of 3d transition metals (Cr, Ma, Fe, Co, Ni).Translated from Izvestiya VUZ. Fizika, No. 12, pp. 36–39, December, 1973.     

Nano-scale metal multilayers produced by repeated press-rolling

Abstract

Multilayer structured alloys which have a layer thickness less than 10 nm have been produced by the application of repeated pressing and rolling to the initially macroscopically thick layered sample. The TEM observation of a Ag/Fe sample revealed a regular alternate lamination of Ag and Fe with the layer thickness in the range of 10 nm. The measured electrical resistivity showed a large dependence on the applied magnetic field which is characteristic to the composite structure of magnetic and non-magnetic metals in the thickness range of nanometers.     

Metastable surface alloys produced by ion implantation,laser and electron beam treatment

Ion Implantation, Laser and Electron-beam Treatment (LET) of metals have been employed extensively to produce metastable surface alloys. Recent published work on implanted alloys is reviewed first. The dilute implanted alloys (solute concentration <10 at. %) are shown to lead to crystalline metastable solid solutions. At higher solute concentrations, an amorphous phase has been observed for several binary systems and recently for a ternary system. The physical mechanisms at play, are discussed in detail. A review of the surface alloys produced by LET of metals is then presented—with an emphasis on the mechanisms involved. In particular, general criteria governing formation of metastable solid solutions under LET are proposed and shown to have excellent agreement with available data on metals and Si.     

Structural and magnetic phase formation in nanophase brass—iron electron compounds

Starting with Cu0.65Zn0.35 with an e/a ratio of 1.35 we studied the phase formation in nanophase (Cu_0.65Zn_0.35)_1?x Fe _x alloys in the concentration range 0.1 ≤x ≤0.7 to see the effect of altering the electron concentration. The evolution of bcc phase from the fcc phase as a function of Fe concentration was investigated by Mössbauer spectroscopy and X-ray diffraction. The grain size, lattice parameters, and average hyperfine magnetic field distributions were estimated for the nanophase alloys. The fcc phase was observed to persist up to 40 atomic per cent Fe substitutions, a mixed (fcc + bcc) phase region up to 70 atomic per cent Fe and bcc phase beyond 70 atomic per cent Fe. The magnetic state of the alloys changed from nonmagnetic forx ≤0.3 to magnetically ordered state at room temperature forx ≤0.33, which lies in the fcc phase region. The fcc phase alloys of Fe with non-magnetic metals have very low magnetic transition temperatures. However, in this system the room temperature state is unusually magnetic     

Magnetische zustände in den kfz legierungen der 3d-übergangsmetalle

By representing the critical temperatures for magnetic order according to the number of outer (s + d) electrons per atom e/a, a systematic connection of the magnetic states in fcc alloys of the 3d-transition metals may be recognized. There exist two distinct groups of alloys exhibiting antiferromagnetic and ferromagnetic order, respectively. The transition from antiferromagnetism to ferromagnetism proceeds in the range 8.0 < e/a < 8.4. In the transition range magnetically heterogeneous states will appear.     

Probing the local,electronic and magnetic structure of matter under extreme conditions of temperature and pressure

ABSTRACT

In this paper we present recent achievements in the field of investigation of the local, electronic and magnetic structure of the matter under extreme conditions of pressure and temperature. These results were obtained thanks to the coupling of a compact laser heating system to the energy-dispersive XAS technique available on the ID24 beamline at the ESRF synchrotron. The examples chosen concern the melting and the liquid structure of 3d metals and alloys under high pressures (HPs) and the observation of temperature-induced spin crossover in FeCO₃ at HP.     

Deformation hardening and the temperature dependence of the mechanical properties of ternary ordering alloys. Part II

Yield point, hardening factor, and elastic modulus are reported as functions of quenching and test temperatures for the alloys Ni₃(Fe + 3 at% Al), Ni₃(Fe + 3 at% Mn). A maximum is found in the mechanical properties near the critical temperature T_cr; this does not occur for alloys in the disordered state. The deformation aging under load is examined near this maximum and at 200 ° C. A range of linear hardening occurs up to e of 15–18% in ordered alloys, which is replaced by a range of decreasing hardening coefficient at higher . The results are discussed by reference to earlier ones for Ni₃Fe, Ni₃(FeCr). Ni₃(FeMo).     

Mössbauer effect study of antiferromagnetic Fe–Mn–Si alloys

Antiferromagnetic Fe–30Mn–Si alloys containing 2.0–8.7 at.% Si are known to exhibit several attractive physical properties at Néel temperatures which render them candidate materials for functional alloys applications. The Néel transitions and anomalous transport phenomena have been studied extensively in a wide temperature range. In the present work, the hyperfine interactions are studied by Mössbauer spectroscopy measured at temperatures 95–623 K. It is found that the Mössbauer spectra are singlets at temperatures above the Néel temperature and doublets below the Néel temperature. The alloys have a small hyperfine field around the Fe nuclei below the Néel temperature and the hyperfine field increases linearly with increasing silicon concentration. This can be explained by the presence of a localised net magnetic moment on the Fe nuclei which is induced by the silicon atoms. A decrease in isomer shift with increasing silicon concentration is observed and this can be accounted for by the change in the occupation of the Fe 3d shell. There is a small quadrupole splitting, it increases with increasing silicon concentration, and is consistent with the lattice shrinking and magnetostriction.