Department of Earth Sciences, Sapienza University of Rome, P. le Aldo Moro 5, Rome, Italy.
Department of Basic and Applied Sciences for Engineering, Sapienza University of Rome, Via Antonio Scarpa 16, Rome, Italy.
Sci Rep. 2019 Sep 3;9(1):12668. doi: 10.1038/s41598-019-48941-4.
A collection of ancient Roman orichalcum coins, i.e., a copper-zinc alloy, minted under the reigns from Caesar to Domitianus, have been characterised using scanning electron microscopy (SEM-EDS) and electron microprobe analysis (EMPA). We studied, for the first time, coins emitted by Romans after the reforms of Augustus (23 B.C.) and Nero (63-64 A.D). These coins, consisting of asses, sestertii, dupondii and semisses, were analysed using non- and invasive analyses, aiming to explore microstructure, corrosive process and to acquire quantitative chemical analysis. The results revealed that the coins are characterized by porous external layers, which are affected by dezincification and decuprification processes. As pictured by the X-ray maps, the elemental distribution of Cu and Zn shows patterns of depletion that in some cases penetrate in deep up to 1 mm. The composition of the un-corroded nucleus is a Cu-Zn alloy containing up to 30% of Zn, typical of coins produced via cementation process.
一批古罗马奥里斯坎铜币，即铜锌合金，在恺撒到多米提安努斯统治时期铸造，已经使用扫描电子显微镜（SEM-EDS）和电子探针分析（EMPA）进行了特征描述。我们首次研究了奥古斯都改革（公元前 23 年）和尼禄（公元 63-64 年）后罗马人发行的硬币。这些硬币由 asses、sestertii、dupondii 和 semisses 组成，使用非侵入性和侵入性分析进行了分析，旨在探索微观结构、腐蚀过程并进行定量化学分析。结果表明，硬币的外部层多孔，受到脱锌和脱铜过程的影响。正如 X 射线图谱所示，Cu 和 Zn 的元素分布呈现出消耗模式，在某些情况下，这种消耗模式会深入到 1mm 深处。未腐蚀核心的成分是一种铜锌合金，含有高达 30%的锌，这是通过渗碳工艺生产硬币的典型特征。
