Anisotropy of surface free energy of cadmium and magnesium

Abstract

The equilibrium shapes of argon gas bubbles in pure cadmium and magnesium have been determined, from which the anisotropy of surface free energy (ASFE) has been determined. The bubbles were bounded by basal, {10·0} prismatic and {10·l} pyramidal facets. From the mean aspect ratios it was determined that y(1010)/y(0001) of cadmium is 1·28 at 115°c and 1·18 at 290°c. For magnesium this ratio of energies has a value of ∼ 1·1 at 340°c. The ASFE of cadmium does not follow the trend of other h.c.p. metals which have been investigated previously. It is shown that large bubbles are slow to equilibrate, whereas very small bubbles may not reveal the true ASFE of the host material due to terms other than surface energy influencing their shape.