A morphological and chemical classification of bronze corrosion features from an Iron Age hoard (Tintignac, France): the effect of metallurgical factors

Authors

  • Giorgia Ghiara University of Genova
  • Christophe Maniquet INRAP Limoges
  • Maria Maddalena Carnasciali University of Genova
  • Paolo Piccardo University of Genova

DOI:

https://doi.org/10.21014/acta_imeko.v11i4.1278

Keywords:

corrosion morphology; Sn bronze; microstructure; tentacle like corrosion; MIC

Abstract

A categorization of corrosion morphologies of archaeological Sn bronzes was carried out on archaeological Iron Age objects. The objects come from a Celtic deposit located in central France (Tintignac, Corrèze) and are dated between 2nd and 3rd cent BC. Being samples of corroded metals taken from a single find spot, parameters connected to the features of the alloy and known to influence the corrosion morphologies were thoroughly considered. Global processes were highlighted, and corrosion mechanisms were characterized with a multi-analytical protocol (SEM-EDS, micro-Raman spectroscopy, image analyses) according to the detected morphology. Elaboration of the results was carried out with a multicomponent approach. Results show the presence of 5 different morphologies correlated to the alloys characteristics of the objects. Alloy composition, microstructure, degree of deformation and grain size were found to influence the corrosion products formed and the morphology of the attack. In particular, the ‘tentacle like corrosion’, associated to a microbial attack was the most susceptible to the effect of metallurgical features: their occurrence is connected to a higher presence of Fe and Pb in the alloy, a homogeneous deformation and a larger grain size.

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Published

2022-11-30

Issue

Section

Research Papers