Atomistic Mechanisms for Grain Boundary Migration

in [001] Twist Boundaries

Presenter: Xinan Yan

 

 

Polycrystalline materials can be viewed as a composite of perfect crystal grains separated from one another by a thin grain boundary region. These boundary regions crucially influence both material function and structural integrity. Grain boundary migration plays a key role in determining the materials properties during thermal mechanical processing. While grain boundary migration has been extensively studied in tilt boundaries, little was known in twist boundaries. In this study, we employed molecular dynamics (MD) simulation to investigate the grain boundary migration in Σ5, Σ13 and general (40.23°) [001] twist boundaries in nickel, introducing embedded atom method. A series of MD simulation were performed to determine the temperature dependence of grain boundary mobility. Simulation showed that twist and tilt boundaries migration was different. Statistical measures with respect to both single atomic motions and string-like cooperative atomic displacements were applied, yielding quantitative mechanisms for the three discussed cases.