向山遺跡出土銅鉢の金属組織と腐食形成層

抄録

  The microstructure of a copper bowl excavated from an Edo-period grave in Mukaiyama Ruins in Nara prefecture has been investigated. The sample was subjected to optical microscopy, scanning electron microscopy, electron probe microanalysis and X-ray diffraction analysis to obtain information about the microstructure of both the base metal and the corroded layers. The bowl was made of copper containing 0.9% lead. Annealing twins were observed in the α-Cu phase, which establishes that the bowl was forged and annealed. The corroded layers were composed mainly of cuprite, malachite and copper phosphate. It is thought that the copper phosphate acted as an inhibitor to corrosion.