抄録
The morphology of dislocation etch pits on the (111) surface of Cu crystal etched with (NH4)2S2O8–NH4OH–NH4Br solutions has been studied by microscopic and interferometric observations. The composition, stirring and temperature of the etchant and the concentration of Al in Cu crystal are varied, and their effects on the etching action are determined. When the ratio of concentrations of (NH4)2S2O8, NH4OH and NH4Br is 1–1.5: 6: 0.3, the etch pits take the form of a regular triangle surrounded with ⟨110⟩ sides, while, off this ratio, they become more or less rounded. The etch pit size increases with an increase of (NH4)2S2O8 concentration and with a decrease of NH4Br concentration in the etchant. When the etchant is stirred, the etch pits grow large keeping the shape unchanged. Such a tendency is also indicated when the etchant temperature is raised. When Al atoms are distributed in Cu crystal, the etch pits become small and rounded, though the straight-sided ones are revealed by etching with the etchant containing high concentration of (NH4)2S2O8. These effects are discussed on the basis of kink models in crystal dissolution.
