高純度銅双結晶の対称傾角粒界における腐食反応とその特異形態

摘要

Grain boundary ridges, which form as a result of unusual reaction of grain boundaries with an aqueous corrosive environment, has been investigated using high-purity copper bicrystals with a symmetrical [110]-tilt grain boundary. A critical misorientation, which divides the formation of a ridge and a groove, was found to be near 90 degrees. It was found that a corrosion groove formed at the grain boundaries in the beginning of corrosion, but subsequently replaced by a ridge. An applied anodic potential restrained the development of a ridge, demonstrating that the formation of the ridges is a result of cathodic reaction at the grain boundaries and anodic reaction at the grain interiors under a rest potential. It is suggested that anisotropic rate of dissolution and resulting corrosion facets near the grain boundaries are closely associated with the unusual electrochemical reaction of the grain boundaries in the aqueous environment.