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Materials Data on Cu3Au by Materials Project
Cu3Au is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Au is bonded to twelve equivalent Cu atoms to form AuCu12 cuboctahedra that share corners with twelve equivalent AuCu12 cuboctahedra, edges with twenty-four equivalent CuCu8Au4 cuboctahedra, faces with six equivalent AuCu12 cuboctahedra, and faces with twelve equivalent CuCu8Au4 cuboctahedra. All Au–Cu bond lengths are 2.67 Å. Cu is bonded to four equivalent Au and eight equivalent Cu atoms to form distorted CuCu8Au4 cuboctahedra that share corners with twelve equivalent CuCu8Au4 cuboctahedra, edges with eight equivalent AuCu12 cuboctahedra, edges with sixteen equivalent CuCu8Au4 cuboctahedra, faces with four equivalent AuCu12 cuboctahedra, and faces with fourteen equivalent CuCu8Au4 cuboctahedra. All Cu–Cu bond lengths are 2.67 Å.
The fine structure of slip lines in disordered Cu3Au.
The fine structure of the slip bands observed on the surface of a deformed Cu3Au single crystal is examined. The separation distance determined between the resolved individual slip lines is used to examine the calculations of other authors relating the passing stress of a dislocation past a dislocation pileup on a nearby parallel glide plane.
Tuning the surface composition of Cu3Au binary alloy
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Microstrain and electron micrographic slip line studies of ordered and disordered Cu3Au
Slip line deformation of ordered and disordered Cu-Au intermetallic single crystals from microstrain and electron micrographic studies
Accurate prediction of short-range order and its effect on thermodynamic, structural, and electronic properties of disordered alloys: exemplified in archetypical Cu 3 Au
Electronic-structure methods based on density-functional theory (DFT) were used to quantify the effect of chemical short-range order (SRO) on thermodynamic, structural, and electronic properties of archetypal face-centered-cubic (fcc) Cu3Au alloy. We showed that SRO can be tuned to alter bonding and lattice dynamics (i.e., phonons) and detail how these properties are changed with SRO. Thermodynamically favorable SRO significantly improved the phase stability of fcc Cu3Au from -0.0343 eV-atom -1 to –0.0682 eV-atom -1 . We used our DFT-based linear-response theory to predict SRO and its electronic origin, and accurately estimate the observed transition temperature, ordering instability (L1 2 ), and Warren-Cowley SRO parameters, in agreement with experiments. The accurate prediction of real-space SRO gives an edge over computationally and resource intensive approaches such as monte-carlo methods or experiments, which will enable large scale molecular dynamic simulations by providing supercells with optimized SRO. Here we also analyzed phonon dispersion and estimated the vibrational entropy change (from 9kB at 300 K to 6kB at 100 K) in fcc Cu3Au. We established from SRO analysis that exclusion of chemical interactions may lead to a skewed view of true properties in chemically complex alloys. The first-principles methods described in this work are generally applicable to any arbitrary solid-solution alloys, including multi-principal-element alloys, therefore, holds promise for designing technologically useful materials.
Field-ion microscopy of ordered Cu-Au alloy.
A method is proposed for overcoming current difficulties in measuring atomic order parameters of nonrefractory metals when using the field-ion microscope (FIM). Near stoichiometric CuAu and Cu3Au were tested by means of this method. Images of substantially fully ordered CuAu and Cu3Au thus obtained are presented and discussed.
On the sputtering of binary compounds
A simple physical model is presented to describe some aspects of the sputtering of compound targets. In particular, expressions are developed for the partial sputtering yields for binary systems in terms of the elemental sputtering rates, the stoichiometric concentrations and surface binding energy. The partial yields depend non-linearly on the bulk target concentrations. Comparison of the theoretical predictions with the data on sputtering of PtSi, NiSi and Cu3Au indicates that the general features are well described.
On the sputtering of binary compounds
A simple physical model is presented to describe some aspects of the sputtering of compound targets. In particular, expressions are developed for the partial sputtering yields for binary systems in terms of the elemental sputtering rates, the stoichiometric concentrations, and surface binding energy. The partial yields depend nonlinearly on the bulk target concentrations. Comparison of the theoretical predictions with the data on sputtering of PtSi, NiSi, and Cu3Au indicates that the general features are well described.
Multilayer relaxation and surface structure of ordered alloys
Using BFS, a new semiempirical method for alloys, we study the surface structure of fcc ordered binary alloys in the Ll(sub 2) structure (Ni3Al and Cu3Au). We show that the surface energy is lowest for the mixed composition truncation of the low-index faces of such systems. Also, we present results for the interlayer relaxations for planes close to the surface, revealing different relaxations for atoms of different species producing a rippled surface layer.
Cu-Au Alloys Using Monte Carlo Simulations and the BFS Method for Alloys
Semi empirical methods have shown considerable promise in aiding in the calculation of many properties of materials. Materials used in engineering applications have defects that occur for various reasons including processing. In this work we present the first application of the BFS method for alloys to describe some aspects of microstructure due to processing for the Cu-Au system (Cu-Au, CuAu3, and Cu3Au). We use finite temperature Monte Carlo calculations, in order to show the influence of 'heat treatment' in the low-temperature phase of the alloy. Although relatively simple, it has enough features that could be used as a first test of the reliability of the technique. The main questions to be answered in this work relate to the existence of low temperature ordered structures for specific concentrations, for example, the ability to distinguish between rather similar phases for equiatomic alloys (CuAu I and CuAu II, the latter characterized by an antiphase boundary separating two identical phases).
Atomistic mechanisms of the initial oxidation of stepped Cu 3 Au ( 100 )
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