The anisotropy of hexagonal close-packed and liquid interface free energy using molecular dynamics simulations based on modified embedded- atom method

E Asadi and MA Zaeem, ACTA MATERIALIA, 107, 337-344 (2016).

DOI: 10.1016/j.actamat.2016.01.043

This work aims to comprehensively study the anisotropy of the hexagonal close-packed (HCP)-liquid interface free energy using molecular dynamics (MD) simulations based on the modified-embedded atom method (MEAM). As a case study, all the simulations are performed for Magnesium (Mg). The solid-liquid coexisting approach is used to accurately calculate the melting point and melting properties. Then, the capillary fluctuation method (CFM) is used to determine the HCP-liquid interface free energy (gamma) and anisotropy parameters. In CFM, a continuous order parameter is employed to accurately locate the HCP-liquid interface location, and the HCP symmetry-adapted spherical harmonics are used to expand gamma in terms of its anisotropy parameters (epsilon(20), epsilon(40), epsilon(60) and epsilon(66)). Eight slip and twinning planes (basal, two prismatic, two pyramidal, and three twinning planes) are considered as the HCP-liquid interface planes. An average HCP-liquid interface free energy of 122.2 (mJ/m(2)), non-zero epsilon(20), epsilon(40), and epsilon(66) parameters, and approximately zero epsilon(60) parameter for Mg are predicted. Using these findings, the first preferred dendrite growth direction in solidification of Mg is predicted as 11 (2) over bar0, which is in agreement with experiments. Also, a second preferred dendrite growth direction for Mg is predicted as 33 (6) over bar2. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Return to Publications page