The kinetics of gallium penetration into aluminum grain boundaries—in situ TEM observations and atomistic models

The penetration behavior of gallium into aluminum grain boundaries was compared with Al grain boundary properties estimated from atomistic computer models. Penetration speeds in individual grain boundaries were measured in situ in the transmission electron microscope (TEM), and the observed Al grain boundaries were simulated using the embedded atom method (EAM). Penetration speeds were relatively slow in low angle grain boundaries and most low Σ boundaries; however, for high Σ boundaries, penetration speeds varied widely and were not correlated with rotation angle or coincidence site lattice (CSL) Σ value. Atomistic computer models suggested that the presence of structural barriers in the grain boundary plane was an important factor in determining penetration speeds.