Interaction of liquid and solid gallium with thin silver films: Synchronized spreading and penetration

The synchronized lateral spreading and through-penetration of liquid and solid gallium (Ga) in supported thin polycrystalline films of silver (Ag) were studied. The spreading and penetration kinetics were presumably controlled by a common mechanism. The spreading rate in the 0.5 μm thick film was found to be constant with time. The activation energies of the process responsible for spreading/penetration of liquid and solid Ga were E_L ≈ 28.9 ± 4.8 kJ mol^-1 and E_S ≈ 48.2 ± 9.6 kJ mol^-1, respectively. Grain boundary grooving, with Ag diffusion out of the groove either through liquid Ga or through solid Ga, was suggested as a possible mechanism of the spreading and penetration. The model proposed reproduced the observed spreading/penetration rates and gave reasonable estimates of the energies E_S and E_L.