Anisotropy of interfacial free energy of some hexagonal close-packed metals

Abstract The equilibrium shapes of inert gas bubbles in zinc were determined by annealing foils which had been supersaturated with argon by ion bombardment. The anisotropy of solid-vapour surface free energy in the temperature range 130-300°C was evaluated by studying bubble shape as a function of annealing temperature. At 300°C the equilibrium bubbles are bounded by basal, {1011} pyramidal and {1010} prismatic facets, and from the mean aspect ratio of the bubbles, it was determined that γ(1010)/γ(0001) = 1.55. At lower temperatures the extent of the prismatic bubble faces is reduced, whereas aspect ratio increases somewhat to 1·75 at 130°C. From these results, the free energy of (0001) zinc surfaces has been determined to be ∼ 600 ergs/cm2, or about six times higher than values obtained by cleavage techniques. Our results are correlated with other experimental data concerning the anisotropy both of solid-vapour and of solid-liquid interfacial free energy in h.c.p. metals. The data for solid vapour interf...