Place: Materials Day 2013, Ruhr-Universität Bochum, Bochum, Germany
Jeff Hoyt, McMaster University, Hamilton, Ontario, Canada
In recent years, molecular dynamics (MD) simulations have been employed to determine thermodynamic and kinetic properties of grain boundaries and several techniques for extracting the mobility such as, curvature, applied stress, the artificial driving force method, random walk analysis and fluctuations, will be reviewed. Although MD techniques have been successful in providing important properties of grain boundaries, less attention has been paid to the mobility and energies of interphase boundaries. In this presentation the use of an embedded atom description of pure Fe to investigate the mobility of the austenite (FCC) – ferrite (BCC) interface will be described. For atomically flat, low index orientations boundaries were observed to be immobile, whereas a boundary tilted slightly from the Nishiyama-Wasserman orientation was found to propagate on an MD time scale. It will be shown that the steps present at the tilted boundary play a key role in the atomic mechanism of growth. In addition, the formation and growth of ferrite from polycrystalline austenite has been investigated. The boundary mobility for various orientations will be discussed and nucleation of ferrite at the grain boundary triple junctions will be compared with predictions from classical theory.