Temperature dependent microstructure of Cu3 Au in the disordered phase

Reichert, H.; Tsatskis, Igor; Moss, S. C.

doi:10.1016/s0927-0256(97)00015-3

Cited by 6 publications

(3 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Last year, such an increase of the peak separation with temperature was observed at equilibrium by Reichert et al [12] for the disordered Cu 3 Au alloy. Moss and Reichert [13,14] found the same behaviour by analysing the Monte Carlo simulation results of Roelofs et al [15] for the Cu-14.4 at.% Al alloy. In the latter work the inverse Monte Carlo pair interactions were determined from the experimental diffuse intensity at a single temperature and subsequently used to generate the Monte Carlo intensities at other temperatures.…”

Section: Introductionmentioning

confidence: 58%

“…In the latter work the inverse Monte Carlo pair interactions were determined from the experimental diffuse intensity at a single temperature and subsequently used to generate the Monte Carlo intensities at other temperatures. The theory of the temperature dependence of the splitting was proposed by Tsatskis [14,16]; it identifies the wavevector dependence of the self-energy of the pair correlation function (PCF) as the origin of this effect. The self-energy (k) and the interaction term 2βV (k) enter the expression for the SRO diffuse intensity on an equal footing (equation (2.1a) below).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Short-range order in a steady state of irradiated Cu-Pd alloys: comparison with fluctuations at thermal equilibrium

Tsatskis¹,

Salje

1998

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

The equilibrium short-range order (SRO) in Cu-Pd alloys is studied theoretically. The evolution of the Fermi surface-related splitting of the (110) diffuse intensity peak with changing temperature is examined. The results are compared with experimental observations for electron-irradiated samples in a steady state, for which the temperature dependence of the splitting was previously found in the composition range from 20 to 28 at.% Pd. The equilibrium state is studied by analysing available experimental and theoretical results and using a recently proposed alpha-expansion theory of SRO which is able to describe the temperature-dependent splitting. It is found that the electronic-structure calculations in the framework of the Korringa-Kohn-Rostoker coherent potential approximation overestimate the experimental peak splitting. This discrepancy is attributed to the shift of the intensity peaks with respect to the positions of the corresponding reciprocal-space minima of the effective interatomic interaction towards the (110) and equivalent positions. Combined with an assumption about monotonicity of the temperature behaviour of the splitting, such shift implies an increase of the splitting with increasing temperature for all compositions considered in this study. The alpha-expansion calculations seem to confirm this conclusion. 05.50+q, 64.60.Cn, 61.66.Dk, 71.18+y

show abstract

Section: Introductionmentioning

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Short-range order in a steady state of irradiated Cu-Pd alloys: comparison with fluctuations at thermal equilibrium

Tsatskis¹,

Salje

1998

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

show abstract

“…Other systems, such as Cu 3 Au, 28,29 Cu-Pd, 30 and Cu-Al, 32 display similar features. In particular, a recent experimental study of the split maxima of ␣(q ជ ) in Cu 3 Au has recently been reported: 28 the main result was that the measured split distance, as referred to ͑100͒, increases when the temperature is raised, in contrast to the present situation.…”

Section: Discussionmentioning

confidence: 91%

Experimental and theoretical study of the temperature and concentration dependence of the short-range order in Pt-V alloys

1998

View full text Add to dashboard Cite

We present a detailed theoretical and experimental study of the short-range order in the Pt 1Ϫc V c system at two concentrations ͑cϭ 1 4 and cϭ 1 9 ͒. In situ neutron-scattering experiments were performed in order to measure the short-range-order parameters in the disordered phase. We found a drastic effect of the concentration on the short-range order: in Pt 3 V, the diffuse intensity is spread along the (1k0) directions with maxima at the ͑100͒ positions, despite the stability at low temperature of a DO 22 phase. In contrast, the diffuse intensity in Pt 8 V displays a splitting around the ͑100͒ positions with incommensurate maxima. Through inverse Monte Carlo simulations the two experiments yield, within the Ising model, two sets of effective-pair interactions. Despite quite different short-range-order patterns, the interactions seem nearly concentration independent with a dominant first-neighbors interaction V 1 . This concentration independence allows us to predict the ordered states and the ordering temperatures. In particular, at low temperatures, these interactions stabilize a new phase of composition A 5 B, which to our knowledge has not been observed until now. Finally, we analyze the origin and behavior of the incommensurate split peaks in Pt 8 V within a high-temperature expansion and show analytically that the splitting is due to a large decrease of the influence of V 1 on the short-range order as the concentration and/or the temperature decreases. This analysis shows also that the splitting distance should decrease with increasing temperature, in agreement with our Monte Carlo simulations, and in contrast with all the other alloys which have already been investigated, either experimentally or theoretically. More generally, we discuss the origin of the temperature behavior of a splitting distance in relation with the location in q space of the incommensurate maxima. Using very simple arguments, we show, provided the restriction that the firstneighbor interactions are dominant, that the splitting distance increases or decreases with increasing temperature depending on whether these maxima lie along the (1k0) axis or not.

show abstract

Computation of Diffuse Intensities in Alloys

Johnson

Pinski

Staunton

2002

Characterization of Materials

View full text Add to dashboard Cite

Diffuse intensities in alloys are measured by a variety of techniques, such as x ray, electron, and neutron scattering. Above a structural phase‐transformation boundary, typically in the solid‐solution phase where most materials processing takes place, the diffuse intensities yield valuable information regarding an alloy's tendency to order. This has been a mainstay characterization technique for binary alloys for over half a century. Although multicomponent metallic alloys are the most technologically important, they also pose a great experimental and theoretical challenge. For this reason, a vast majority of experimental and theoretical effort has been made on binary systems, and most investigated “ternary” systems are either limited to a small percentage of ternary solute (say, to investigate electron‐per‐atom effects) or they are pseudo‐binary systems. Thus, for multicomponent alloys the questions are: how can you interpret diffuse scattering experiments on such systems and how does one theoretically predict the ordering behavior? This article discusses an electronic‐based theoretical method for calculating the structural ordering in multicomponent alloys and understanding the electronic origin for this chemical‐ordering behavior. This theory is based on the ideas of concentration waves using a modern electronic‐structure method. Thus, examples show how the electronic origin behind the unusual ordering behavior in a few binary and ternary alloy systems that were not understood prior to the authors, work were determined. From the start, the theoretical approach is compared and contrasted to other complimentary techniques for completeness. In addition, some details are given about the theory and its underpinnings. Importantly, for the more general multicomponent case, in the context of concentration waves how to extract more information from diffuse‐scattering experimental data is described. For binary or multicomponent alloys, the atomic short‐range order (ASRO) in the disordered solid‐solution phase is related to the thermally induced concentration fluctuations in the alloy. Such fluctuations in the chemical site occupations are the (infinitesimal) deviations from a homogeneously random state, and are directly related to the chemical pair correlations in the alloy. Thus, the ASRO provides valuable information on the atomic structure to which the disordered alloy is tending. Importantly, the ASRO can be determined experimentally from the diffuse scattering intensities measured in reciprocal space either by x rays, neutrons, or electrons. However, the underlying microscopic or electronic origin for the ASRO cannot be determined from such experiments, only their observed indirect effect on the order. Therefore, the calculation of diffuse intensities in high‐temperature, disordered alloys based on electronic density‐functional theory and the subsequent connection of those intensities to its microscopic origin(s) provides a fundamental understanding of the experimental data and phase instabilities. These are the principal themes that are emphasized in this article.

show abstract

Temperature dependent microstructure of Cu3 Au in the disordered phase

Cited by 6 publications

References 35 publications

Short-range order in a steady state of irradiated Cu-Pd alloys: comparison with fluctuations at thermal equilibrium

Short-range order in a steady state of irradiated Cu-Pd alloys: comparison with fluctuations at thermal equilibrium

Experimental and theoretical study of the temperature and concentration dependence of the short-range order in Pt-V alloys

Computation of Diffuse Intensities in Alloys

Contact Info

Product

Resources

About