Atomistic Simulations of Dislocation-Interface Interactions in the Cu-Ni Multilayer System

1999 ◽  
Vol 578 ◽  
Author(s):  
Satish I. Rao ◽  
Peter M. Hazzledine
Keyword(s):  
Yield Strength ◽  
Elastic Moduli ◽  
Lattice Parameter ◽  
Stacking Fault ◽  
Chemical Effect ◽  
Atomistic Simulations ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Coherency Strains ◽  
Stacking Fault Energies

AbstractMultilayered Cu-Ni has a peak yield strength four orders of magnitude higher than either Cu or Ni because the multitude of interfaces obstruct glissile dislocations. The barrier strengths of the interfaces may be traced to four mismatches across an interface: modulus, lattice parameter, chemical and slip geometry. This paper describes sample embedded atom method (EAM) simulations of dislocations crossing interfaces, designed to separate the effects of the four mismatches. The results confirm some classical calculations and emphasize the importance of three new effects (i) an interface-chemical effect in which dislocations are trapped by core spreading in the interface, (ii) a coherency-chemical effect caused by coherency strains changing effective stacking fault energies and (iii) a coherency-modulus effect in which coherency strains change elastic moduli (and hence the Koehler stress) significantly.

scholarly journals First Principles Investigation on Thermodynamic Properties and Stacking Fault Energy of Paramagnetic Nickel at High Temperatures

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 319
Author(s):  
Jing Zhang ◽  
Pavel A. Korzhavyi
Keyword(s):  
Mechanical Properties ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Temperature Dependence ◽  
First Principles ◽  
Elastic Moduli ◽  
Stacking Faults ◽  
Lattice Parameter ◽  
Stacking Fault ◽  
Stacking Fault Energies

Reliable data on the temperature dependence of thermodynamic properties of alloy phases are very useful for modeling the behavior of high-temperature materials such as nickel-based superalloys. Moreover, for predicting the mechanical properties of such alloys, additional information on the energy of lattice defects (e.g., stacking faults) at high temperatures is highly desirable, but difficult to obtain experimentally. In this study, we use first-principles calculations, in conjunction with a quasi-harmonic Debye model, to evaluate the Helmholtz free energy of paramagnetic nickel as a function of temperature and volume, taking into account the electronic, magnetic, and vibrational contributions. The thermodynamic properties of Ni, such as the equilibrium lattice parameter and elastic moduli, are derived from the free energy in the temperature range from 800 to 1600 K and compared with available experimental data. The derived temperature dependence of the lattice parameter is then used for calculating the energies of intrinsic and extrinsic stacking faults in paramagnetic Ni. The stacking fault energies have been evaluated according to three different methodologies, the axial-next-nearest-neighbor Ising (ANNNI) model, the tilted supercell approach, and the slab supercell approach. The results show that the elastic moduli and stacking fault energies of Ni decrease with increasing temperature. This “softening” effect of temperature on the mechanical properties of nickel is mainly due to thermal expansion, and partly due to magnetic free energy contribution.

Calculations of stacking fault energy for fcc metals and their alloys based on an improved embedded-atom method

1995 ◽  
Vol 96 (10) ◽  
pp. 729-734 ◽  
Author(s):  
Xiliang Nie ◽  
Renhui Wang ◽  
Yiying Ye ◽  
Yumei Zhou ◽  
Dingsheng Wang
Keyword(s):  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Embedded Atom Method ◽  
Fcc Metals ◽  
Embedded Atom

Atomistic Simulations of the Mechanical Response of Copper/Polybutadiene Joints under Stress

2009 ◽  
Vol 1224 ◽  
Author(s):  
Fidel Orlando Valega Mackenzie ◽  
Barend J. Thijsse
Keyword(s):  
Mechanical Response ◽  
Polymer System ◽  
Atomistic Simulations ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Numerical Studies ◽  
Universal Force Field ◽  
Dynamics Simulations ◽  
Metal Melting Point ◽  
Metal Polymer

AbstractMetal/polymer system joints are widely encountered nowadays in microscopic structures such as displays and microchips. In several critical cases they undergo thermal and mechanical loading, with contact failure due to fracture as a possible consequence. Because of their variety in nature and composition metal/polymer joints have become major challenges for experimental, theoretical, and numerical studies. Here we report on results of molecular dynamics simulations carried out to study the mechanical response of a metal/polymer joint, in this case the Cu/polybutadiene model system. The behavior of Cu and the cross-linked polybutadiene are modeled, respectively, by the Embedded Atom Method (EAM) and the Universal Force Field (UFF). Loading is applied under compression. Different potentials are used to describe the interactions in the metal/polymer interface, which allows us to qualitatively analyze possible mechanisms of failure in these joints, below the metal melting point and above the polymer glass transition temperatures.

scholarly journals Energy calculation of the stacking fault in fcc metals by embedded-atom method

2006 ◽  
Vol 55 (1) ◽  
pp. 393
Author(s):  
Zhang Jian-Min ◽  
Wu Xi-Jun ◽  
Huang Yu-Hong ◽  
Xu Ke-Wei
Keyword(s):  
Stacking Fault ◽  
Embedded Atom Method ◽  
Energy Calculation ◽  
Fcc Metals ◽  
Embedded Atom

Atomistic Simulations of fcc Pt75Ni25 and Pt75Re25 Cubo-octahedral Nanoparticles

2004 ◽  
Vol 818 ◽  
Author(s):  
Guofeng Wang ◽  
M.A. Van Hove ◽  
P.N. Ross ◽  
M.I. Baskes
Keyword(s):  
Sandwich Structure ◽  
Surface Segregation ◽  
Atomistic Simulations ◽  
Embedded Atom Method ◽  
Interatomic Potentials ◽  
Atomic Shell ◽  
Embedded Atom ◽  
The Monte Carlo Method ◽  
Equilibrium Structures ◽  
Modified Embedded Atom Method

AbstractWe have developed interatomic potentials for Pt-Ni and Pt-Re alloys within the modified embedded atom method (MEAM). Furthermore, we applied these potentials to study the equilibrium structures of Pt75Ni25 and Pt75Re25 nanoparticles at T=600 K using the Monte Carlo method. In this work, the nanoparticles are assumed to have disordered fcc cubo-octahedral shapes (terminated by {111} and {100} facets) and contain from 586 to 4033 atoms (corresponding to a diameter from 2.5 to 5 nm). It was found that, due to surface segregation, (1) the Pt75Ni25 nanoparticles form a surface-sandwich structure: the Pt atoms are enriched in the outermost and third atomic shells, while the Ni atoms are enriched in the second atomic shell; (2) the equilibrium Pt75Re25 nanoparticles adopt a core-shell structure: a Pt-enriched shell surrounding a Pt-deficient core.

Methods for Determining Vacancy Formation Thermodynamic

1992 ◽  
Vol 291 ◽  
Author(s):  
L. Zhao ◽  
R. Najafabadl ◽  
D. J. Srolovitz
Keyword(s):  
Vacancy Concentration ◽  
Excess Entropy ◽  
Vacancy Formation ◽  
Atomistic Simulations ◽  
Embedded Atom Method ◽  
Simple Extension ◽  
Interatomic Potentials ◽  
Harmonic Method ◽  
Embedded Atom ◽  
Formation Thermodynamics

ABSTRACTThe vacancy formation thermodynamics in six fcc metals Ag, Au, Cu, Ni, Pd and Pt are determined from atomistic simulations as a function of temperature. This investigation is performed using the Embedded Atom Method interatomic potentials and the finite temperature properties are determined within the local harmonic and the quasiharmonic frameworks. We find that the temperature dependence of the vacancy formation energy can make a significant contribution to the vacancy concentration at high temperatures. An additional goal of the present study is to evaluate the accuracy of the local harmonic method under circumstances in which the excess entropy associated with the formation of a defect is very small. Our data demonstrate that while the errors associated with determining the vacancy formation entropy in the local harmonic model are large, a simple extension to the local harmonic method yields thermodynamic properties comparable to that obtained in the quasiharmonic model, but with much higher computational efficiency.

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