Composition and Microstructures of Imperial Brass Chinese Coins

Abstract:

Twenty brass Chinese cash coins with complex compositions were studied for a better understanding of the metallurgical cash production in China, during the 17th, 18th and 19th centuries. Elemental composition was obtained through energy-dispersive micro X-ray fluorescence spectrometry of small cleaned areas on the coins rims. Results showed that these brass alloys (Cu-Zn) frequently contain up to 3% Sn, have highly variable Pb content (from n.d. up to 14%) and Fe, Sb, and As as minor elements. Microstructures were assessed by optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, and preliminary micro X-ray diffraction analysis. All the coins present typical as-cast microstructures although very fine-grained, which are supported by binary (Cu-Zn) and ternary (Cu-Zn-Sn) equilibrium phase diagrams, that explain microstructural differences due to the presence of Sn in these brasses.

• Periodical: Materials Science Forum (Volumes 636-637)
• Pages: 531-537
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.636-637.531
• Online since: January 2010
• Authors: M.J. Furtado, Rui Jorge C. Silva, M.F. Araújo, Francisco Manuel Braz Fernandes
• Keywords: Brass Alloys, Chinese Coin, Cryo-SEM, Cu-Zn Binary System, Cu-Zn-Sn Ternary System, EDXRF, Elemental Composition, Microstructure

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