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Ref ID: 22395
Ref Type: Book Section
Authors: Furtado, Maria João
Silva, Rui J. C.
Araújo, M. Fátima
Fernandes, Francisco M. Braz
Title: Multiphase microstructures on late imperial Chinese brass coins
Date: 2015
Source: Metals and civilizations
Place of Publication: Bangalore, India
Publisher: National Institute of Advanced Studies
Notes: Proceedings of the Seventh International Conference on the Beginnings of the Use of Metals and Alloys (BUMA VII)
Abstract: Thirty-five brass Chinese cash coins from three different reigns and of distinct provenances were studied to characterize the composition of Chinese coins in the period from the 17th to the 19th century. Energy-dispersive X-ray fluorescence spectrometry (EDXRF) of the coins surface as well as energy-dispersive micro X-ray fluorescence spectrometry (micro-EDXRF) of small cleaned areas on the coins rims was performed to obtain elemental composition. Optical microscopy (OM) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) were used to examine their microstructures. For a few selected coins, micro X-ray diffractometry (micro-XRD) was used to identify less common phases in brasses. Results showed that these brass alloys (Cu-Zn) frequently contain up to 3 wt.% Sn or the corresponding value in Sb, have highly variable Pb content (from <i/>n.d.</i> up to 14 wt.%) and although Fe and As appear mainly as minor elements, their content in the last reign rises up to 6 wt.% and 4 wt.%, respectively. The coins present very typical fine-grained as-cast microstructures, which could be interpreted by binary (Cu-Zn) and ternary (Cu-Zn-Sn) equilibrium phase diagrams, the latter explaining the main microstructural differences due to Sn or Sb in these brasses. Fe and As rich phases were observed in a few coins of later reigns.
Date Created: 4/11/2016
Editors: Srinivasam, Sharada
Ranganathan, Srinivasa
Giumlia-Mair, Alessandra
Page Start: 129
Page End: 136