journal article

Journal Article

Text

Computational Materials Science. 2020, 183, p. 109907

Energetics of heterogeneous Mg {101¯2} deformation twinning migration using an atomistically informed phase-field model

Ishii, Akio

Elsevier

English

Text

2020-07-10

https://doi.org/10.1016/j.commatsci.2020.109907

Akio Ishii, Energetics of heterogeneous Mg {101¯2} deformation twinning migration using an atomistically informed phase-field model, Computational Materials Science, Volume 183, 2020, 109907, ISSN 0927-0256, https://doi.org/10.1016/j.commatsci.2020.109907.

We have constructed an atomistically informed phase-field model for the quantitative energetic analysis of phase transformations. In our model, to describe the general phase transformation with a non-linear correlation between displacive and diffusive modes, we have defined two order parameters, γ and ϕ, which describe the lattice distortion (displacive mode) and shuffling (diffusive mode), respectively. Our method provides a way to introduce the energetics from atomistic simulations to the phase-field model, describes γ and ϕ in an atomic model, and derives phase-field parameters from the free energy calculated by atomistic simulation. As an application of our model, we used the energetics obtained from atomistic simulations using a density functional theory potential, and we calculated the free energy change during the heterogeneous {101¯2} twin migration of hexagonally close-packed (HCP) Mg, which can be considered as a lattice distortion and shuffling mixed phase transformation, by combining our phase-field model with the nudged elastic band method. The activation energy, and the critical nucleus size of the heterogeneous {101¯2} twin migration under a set stress were derived. The critical c-axis tensile stress (athermal stress), at which the activation energy becomes zero, is consistent with the experimental yield stress of {101¯2} for the twinning deformation of HCP Mg nanopillars in tensile tests. The critical nucleus size of the heterogeneous {101¯2} twin migration is on the range of nanometers under several hundred megapascals stress, which is consistent with the experimental observation of nanotwins.

This is an open access article under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International license.

89305

Energetics of heterogeneous Mg {101¯2} deformation twinning migration using an atomistically informed phase-field model

Ishii, Akio

Elsevier

English

2020-07-10

Computational Materials Science

183

109907

https://doi.org/10.1016/j.commatsci.2020.109907

https://hdl.handle.net/11094/89305