Crystal size and direction dependence of the elastic properties of Cu3Sn through molecular dynamics simulation and nanoindentation testing

The study aims at exploring the elastic properties of orthorhombic Cu3Sn crystals through a proposed molecular dynamics (MD) simulation model based on the modified embedded atom method (MEAM) and nanoindentation testing. The focuses of the study are placed on their dependence on the crystal size and direction. The electronic nature of single crystal Cu3Sn is also examined by using first-principles calculations based on density function theory (DFT). According to continuum mechanics, the elastic stiffness coefficients of the single crystal Cu3Sn are derived from the calculated energy, and used in the generalized Hook's law in compliance form to compute the associated elastic constants. The simulated elastic properties are compared with the results of the published first-principles calculations. For comparison with the present nanoindentation finding and the other published experimental data, the effective elastic properties of the polycrystalline Cu3Sn together with their size dependence are also derived using the Voigt-Reuss bounds and Voigt-Reuss-Hill average based on the calculated tingle crystal data. The simulation results show that the orthorhombic Cu3Sn crystals exhibit a high elastic anisotropy, which has been also confirmed by the electronic structure analysis, and also a strong size and direction dependence of elasticity. In addition, the calculated effective elastic properties of the polycrystalline Cu3Sn agree well with the present nanoindentation results and the published theoretical/experimental data. (C) 2012 Elsevier Ltd. All rights reserved.