Article

Molecular dynamics study of Cu-Pd ordered alloys

Journal of Achievements in Materials and Manufacturing Engineering 01/2008;
Source: DOAJ

ABSTRACT Purpose: The goal of the paper is to study the molecular dynamics of Cu-Pd ordered alloys.Design/methodology/approach: The thermal and mechanical properties of Cu, Pd pure metals and their ordered intermetallic alloys of Cu3Pd(L12) and CuPd3(L12) are studied by using the molecular dynamics simulation. The melting behavior of the metals considered in this work is studied by utilizing quantum Sutton-Chen (Q-SC) many-body potential. The effects of temperature and concentration on the physical properties of Cu-Pd system are analyzed.Findings: A wide range of properties of Cu, Pd pure metals and their Cu3Pd and CuPd3 ordered intermetallics is presented. It was found that this potential is suitable to give the general characteristics of the melting process in these systems. Practical implications: The simulation results such as cohesive energy, density, elastic constants, bulk modulus, heat capacity, thermal expansion and melting points are in good agreement with the available experimental data and other theoretical calculations.Originality/value: To the best our knowledge this work presents, for the first time, a wide range of physical properties of alloys focusing on Cu-Pd ordered compounds.

0 Bookmarks
 · 
89 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: We have evaluated interatomic potentials of Cu, Au and Cu-Au 0953-8984/10/48/018/img9 ordered alloys in the framework of the second-moment approximation to the tight-binding theory by fitting to the volume dependence of the total energy of these materials computed by first-principles augmented-plane-wave calculations. We have applied this scheme to calculate the bulk modulus and elastic constants of the pure elements and alloys and we have obtained a good agreement with experiment. We also have performed molecular-dynamics simulations at various temperatures, deducing the temperature dependence of the lattice constants and the atomic mean square displacements, as well as the phonon density of states and the phonon-dispersion curves of the ordered alloys. A satisfactory accuracy was obtained, comparable to previous works based on the same approximation, but resulting from fitting to various experimental quantities.
    Journal of Physics Condensed Matter 01/1998; 101(48):10979-10990. · 2.22 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We present a simple method to improve the accuracy of the calculated heat of mixing for the Cu-Pd alloy within the formalism of the molecular dynamics/ Monte Carlo-corrected effective medium (MD/MC-CEM) theory by adding a fitted Morse potential to the pair interaction between Cu and Pd atoms. This leads to a much better agreement between the theoretical and experimental values of heats of mixing for five different compositions of the Cu-Pd alloy in the bulk phases. Using this newly fitted model, we have performed simulations on CuPd clusters consisting of 50-10000 atoms with fcc and bcc structures. Our calculations show that in the range of cluster sizes of several thousand atoms, the fcc structure is energetically favoured over the bcc structure. We estimate an approximate size for the fcc to bcc (CsCl, known bulk structure for CuPd) transition in these clusters to be around 10000 atoms. Additionally, we have also performed calculations of the X-ray diffraction patterns of a variety of cluster geometries and sizes. The calculated X-ray diffraction pattern of a slightly distorted fcc cluster exhibits the main features observed in the available experimental diffraction patterns of colloidal bimetallic catalysts of CuPd. The calculated diffraction patterns of bcc clusters are quite different from the experimental data.
    Philosophical Magazine A 08/1999; 79(8):2025-2049.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The structures and energetics of Cu-Au alloys over a wide range of temperatures are studied using a combination of quasi-harmonic (QH) lattice dynamics and Monte Carlo (MC) simulations at constant temperature and constant pressure. The many-body potential used is fitted to room-temperature experimental data taking vibrational contributions into account. Transitions to the disordered phases are studied using MC simulations in which not only anisotropic deformation of the unit cell and atomic movements are allowed, but also exchange of atoms of different type is explicitly considered. Our calculations reproduce all characteristic features of the order-disorder transitions, including the characteristic peaks in the plots of heat capacity as a function of temperature.
    Modelling and Simulation in Materials Science and Engineering 05/2000; 8(3):389. · 1.93 Impact Factor

Full-text (2 Sources)

View
191 Downloads
Available from
May 21, 2014