and Simulation 1
Capturing the kinetics of complex phase boundary migration: An adaptive kinetic Monte Carlo study
Jutta Rogal, Ruhr-Universität Bochum, Bochum, GermanyJuliana Duncan, University of Texas at Austin, Austin, USAAri Harjunmaa, ICAMS, Ruhr-Universität Bochum, Bochum, GermanyRye Terrell, University of Texas at Austin, Austin, USARalf Drautz, ICAMS, Ruhr-Universität Bochum, Bochum, GermanyGraeme Henkelman, University of Texas at Austin, Austin, Texas
Atomistic modelling of the dynamics of phase transformations is a particularly challenging task. If the mechanism of the phase transformation is governed by so-called rare events, the time scale of interest will reach far beyond the capabilities of regular molecular dynamics simulations.
The atomistic rearrangements during solid-solid phase transformations in bulk systems involve massive structural changes including concerted multi-atom processes. The interface between two structurally different phases leads to a complex energy landscape that needs to be explored during the dynamical evolution of the interface. Here, we employ an adaptive kinetic Monte Carlo (AKMC) approach to investigate such processes at the interface between cubic and topologically close-packed phases in transition metals.
In particular, we investigate the transformation between BCC and A15 in molybdenum. During the dynamical simulations a finite, disordered interface region evolves to compensate the structural mismatch between the two crystal phases. This disordered interface region makes it difficult to identify a single transformation mechanism. Still, from our simulations we extract a rate for the layer transformation which we relate to an effective barrier for the transformation mechanism and discuss the corresponding features of the complex energy landscape along the transformation path.