Atomistic calculations of interface elastic properties in noncoherent metallic bilayers

Abstract

The paper describes theoretical and computational studies associated with the interface elastic properties of noncoherent metallic bicrystals. Analytical forms of interface energy, interface stresses, and interface elastic constants are derived in terms of interatomic potential functions. Embedded-atom method potentials are then incorporated into the model to compute these excess thermodynamics variables, using energy minimization in a parallel computing environment. The proposed model is validated by calculating surface thermodynamic variables and comparing them with preexisting data. Next, the interface elastic properties of several fcc-fcc bicrystals are computed. The excess energies and stresses of interfaces are smaller than those on free surfaces of the same crystal orientations. In addition, no negative values of interface stresses are observed. Current results can be applied to various heterogeneous materials where interfaces assume a prominent role in the systems' mechanical behavior.

Determinations of both length scale and surface elastic parameters for fcc metals

“…In these tables, the results based on both unrelaxed configuration ("U") and relaxed configuration ("R") are shown. Johnson potential is used, and the corresponding results are compared with others results based on the MD simulation [29].…”

“…Johnson potential can be read as: Table 2 Surface elastic parameters of the (100) free surface calculated for fcc metals using the Johnson EAM potential (the first row); the next row represents the corresponding results extracted from [29]. Units: eV/Å 2 .…”

“…where coefficients f e , ϕ e , E c , α, β, γ are given in [29], ρ e is the electronic density when the atom is at equilibrium state.…”

“…Shenoy [28] studied the surface constitutive relation and derived the surface elastic constants, and he obtained the formulas of the surface elastic parameters. Mi et al [29] and Pahlevani and Shodja [30] investigated the surface stress and the surface elastic parameters through molecular dynamics (MD) simulation.…”

Fast evaluation of local elastic constants and its application to nanosized structures

“…Overall, this new approach will be a powerful tool for the modeling and simulation of other inhomogeneous materials, such as the interphase of polymer-based nano-composites [45], interface formed between different crystallographic directions [46], etc. It will enables validation of the various continuum models on the prediction of the effective modulus for heterogeneous materials; the approach can be used to estimate the mechanical performances that are difficult to obtain experimentally; and it will give us a means to explore and compare the roles of polymer-substrate interactions and geometrical constraints on elastic properties.…”