Application of the Embedded-atom Method to Liquid Binary Cu-Ni Alloys

A simple analytic embedded-atom model of monoatoms that includes more than nearest neighbours has been extended to study properties of binary liquid Cu-Ni alloys, here the two-body potential between different species of atoms is taken as a function of the two-body potential for the pure metals with a unique form which yields alloy models with the same invariance to electron density transformations as monoatomic models. Faber-Ziman structure factors have been computed by molecular dynamics simulation on the base of this model. The results are in good agreement with experimental data given by Waseda, thus supporting the overall validity of the approach, especially for cross potential of Cu-Ni pair. Further, a detailed description of structure of binary liquid Cu-Ni alloys with different compositions have been performed using pair analysis and bond orientational order method etc., and then the chemical short range order has also been examined to reveal the structural characterization.

Chen’s lattice inversion embedded-atom method for Ni-Al alloy

The structural properties, the enthalpies of formation, and the mechanical properties of some Ni-Al intermetallic compounds （NiAl, Ni3Al, NiAl3, Ni5Al3, Ni3Al4） are studied by using Chen＇s lattice inversion embedded-atom method （CLI-EAM）. Our calculated lattice parameters and cohesive energies of Ni-A1 compounds are consistent with the experimental and the other EAM results. The results of enthalpy of formation indicate a strong chemical interaction between Ni and Al in the intermetallic compounds. Through analyzing the alloy elastic constants, we find that all the Ni-Al intermetallic compounds discussed are mechanically stable. The bulk moduli of the compounds increase with the increasing Ni concentration. Our results also suggest that NiAl, Ni3Al, NiAl3, and Ni5Al3 are ductile materials with lower ratios of shear modulus to bulk modulus; while Ni3Al4 is brittle with a higher ratio.

The ternary Ni–Al–Co embedded-atom-method potential for γ/γ Ni-based single-crystal superalloys: Construction and application

An Ni-AI-Co system embedded-atom-method potential is constructed for the γ（Ni）/γ＇（Ni3A1） superalloy based on experiments and first-principles calculations. The stacking fault energies （SFEs） of the Ni（Co, A1） random solid solutions are calculated as a function of the concentrations of Co and A1. The calculated SFEs decrease with increasing concentrations of Co and A1, which is consistent with the experimental results. The embedding energy term in the present potential has an important influence on the SFEs of the random solid solutions. The cross-slip processes of a screw dislocation in homogenous Ni（Co） solid solutions are simulated using the present potential and the nudged elastic band method. The cross-slip activation energies increase with increasing Co concentration, which implies that the creep resistance of γ（Ni） may be improved by the addition of Co.

Construction of embedded-atom-method interatomic potentials for alkaline metals (Li,Na,and K) by lattice inversion

The lattice-inversion embedded-atom-method interatomic potential developed previously by us is extended to alkaline metals including Li,Na,and K.It is found that considering interatomic interactions between neighboring atoms of an appropriate distance is a matter of great significance in constructing accurate embedded-atom-method interatomic potentials,especially for the prediction of surface energy.The lattice-inversion embedded-atom-method interatomic potentials for Li,Na,and K are successfully constructed by taking the fourth-neighbor atoms into consideration.These angular-independent potentials markedly promote the accuracy of predicted surface energies,which agree well with experimental results.In addition,the predicted structural stability,elastic constants,formation and migration energies of vacancy,and activation energy of vacancy diffusion are in good agreement with available experimental data and first-principles calculations,and the equilibrium condition is satisfied.

Peridynamic State-Based Models and the Embedded-Atom Model

We investigate connections between nonlocal continuum models and molecular dynamics.A continuous upscaling of molecular dynamics models of the form of the embedded-atom model is presented,providing means for simulating molecular dynamics systems at greatly reduced cost.Results are presented for structured and structureless material models,supported by computational experiments.The nonlocal continuum models are shown to be instances of the state-based peridynamics theory.Connections relating multibody peridynamic models and upscaled nonlocal continuum models are derived.

The influence of 3d-metal alloy additions on the elastic and thermodynamic properties of CuPd_3

Embedded-atom method （EAM） potentials are used to investigate the effects of alloying （e.g. 3d-metals） on the trends of elastic and thermodynamic properties for CuPd3 alloy. Our calculated lattice parameter, cohesive energy, and elastic constants of CuPd3 are consistent with the available experimental and theoretical data. The results of elastic constants indicate that all these alloys are mechanically stable. Further mechanical behavior analysis shows that the additions of Cr, Fe, Co, and Ni could improve the hardness of CuPd3 while V could well increase its ductility. Moreover, in order to evaluate the thermodynamic contribution of 3d-metals, the Debye temperature, phonon density of states, and vibrational entropy for CuMPd6 alloy are also investigated.

Melting Behaviour of Core-Shell Structured Ag-Rh Bimetallic Clusters

The melting behaviour of four typical core-shell structured 309-atom Ag-Rh bimetallic clusters, with decahedral and icosahedral geometric configurations, is investigated by using molecular dynamics simulation, based on the Sutton-Chen potential. The initial atomic configurations are obtained from semi-grand canonical ensemble Monte Carlo simulations. It is found that the melting point temperature Tm increases with the mole fraction of Rh in the bimetallic clusters, and Tm of Ag-Rh icosahedral clusters is higher than those of Ag-Rh decahedral clusters with the same Rh mole fraction. It is also found that the Ag atoms lie on the surface of Ag-Rh bimetallic clusters even after melting.

Relaxed energy and structure of edge dislocation in iron

With modified analytical embedded-atom method and molecular dynamics simulation, this paper simulates the strain energy and the equilibrium core structure of a（100） edge dislocation in BCC metal iron on atomistic scale. In addition, the trapping effect of dislocation on vacancy is investigated as well. The results show that the equilibrium dislocation core is quite narrow and has a C2v symmetry structure. Calculated strain energy Es of the dislocation is a linear function of ln（R/2b） while R ≥ 5.16 A（1A = 0.1 nm）, in excellent agreement with the elasticity theory prediction. Determined core radius and energy are 5.16 A and 0.62 eV/A, respectively. The closer the vacancy to the dislocation line is, the lower the vacancy formation energy is, this fact implies that the dislocation has a trend to trap the vacancy, especially for a separation distance of the vacancy from dislocation line being less than two lattice constants.

Molecular dynamics simulation of surface melting behaviours of the V(110) plane

The modified analytic embedded-atom method and molecular dynamics simulations are applied to the investigation of the surface premelting and melting behaviours of the V（110） plane by calculating the interlayer relaxation, the layer structure factor and atomic snapshots in this paper. The results obtained indicate that the premelting phenomenon occurs on the V（110） surface at about 1800K and then a liquid-like layer, which approximately keeps the same thickness up to 2020K, emerges on it. We discover that the temperature 2020K the V（110） surface starts to melt and is in a completely disordered state at the temperature of 2140K under the melting point for the bulk vanadium.

Simulation of He Behavior in Metals With Embedded Atom Method

The embedded-atom method(EAM)is used to study the behavior of helium in meta-ls.By fitting the measured parameters such as the activation energy and the heat of solution,the EAM potentials of helium in nickel are extracted.Based upon the EAM potentials,thebinding energy and the self-trapping of helium in nickel are investigated with molecular dynam-ics simulation.

生鲜电商企业产地优质资源获取路径分析——基于嵌入式关系的视角

当前,生鲜电商企业的发展面临着巨大的机遇与挑战。除了对冷链物流的建设之外,产地直采这一模式由于具有控制采购成本、提高产品质量和缩短供应链等特点也开始逐渐成为生鲜电商探索新出路的选择。本文通过分析产地优质资源的获取在产地直采过程中的重要性和必要性,以及处于原子式市场交易关系下生鲜电商企业的产地优质资源获取现状,得出与产地优质供应商建立嵌入式关系对生鲜电商企业的产地直采布局意义重大的结论。最后从理论出发,分别从结构嵌入维度和关系嵌入维度给出了如何建立嵌入式关系的可操作路径。本研究成果指导了商业实践,填补了理论空缺。

Molecular dynamics simulation of thermal stability of nanocrystalline vanadium

The microstructure and thermal stability of nanocrystalline vanadium with an average grain size ranging from 2.86 to 7.50 nm are calculated by means of the analytic embedded-atom method and molecular dynamics. The grain boundary and nanocrystal- line grain atoms are differentiated by the common neighbor analysis method. The results indicate that the fraction of grain boundary increases with the grain size decreasing, and the mean energy of atoms is higher than that of coarse crystals. The thermal-stable tem- peratures of nanocrystalline vanadium are determined from the evolution of atomic energy, fraction of grain boundary and radial distribution function. It is shown that the stable tem- perature decreases obviously with the grain size decreasing. In addition the reasons which cause the grain growth of nanocrystalline vanadium are discussed.

Consistent Analytic Embedded Atom Potential for Face-Centered Cubic Metals and Alloys

A consistent empirical embedded-atom potential that includes a long range force was developed for fcc （face-centered cubic） metals and alloys. The proposed potential for pure metals does not require modification of the initial function form when being applied to alloy systems. The potential parameters of this model were determined by fitting lattice constant, three elastic constants, cohesive energy, and vacancy formation energies of the pure metals and the heats of solution of the binary alloys via an optimization technique. Parameters for Ag, AI, Au, Cu, Ni, Pd and Pt were obtained. The obtained parameters were used to calculate the bulk modulus, divacancy formation energy, crystal stability, stacking fault energy, vacancy migration energy, and melting point for each pure metal and the heats of formation and lattice constants for binary alloys. The predicted values were in good agreement with experimental results.