Cu-As alloys with different amounts of As were prepared (1, 2, 3, 4, 5, 6, 7, 11, 15 wt.% As) and cast in iron chill cast moulds. The produced CuAs-ingots (10 x 4 x 0.5 cm) are the base of all further analyses. Since it was not possible to cast ingots in moulds with the same geometry, but different mould material (sand, sandstone, clay), simulations of such castings were carried out with Matlab© and linked with the SDAS in order to calculate the cooling speed (see publications). The following analyses and works were carried out:
1. Establishing out-of-equilibrium phase diagrams of CuAs-alloys with up to 15 wt.% As at different cooling speed (2, 5, 10, 20 K/min) with DTA (Objective 1A)
2. Simulation of prehistoric casting technologies of arsenical bronze with up to 15 wt.% As in different mould materials (terracotta, terracotta at 600°C, tin-bronze, steatite, sand, iron) with Matlab© (Objective 1A)
3. Material characteristics: The color characteristics of different copper alloys, such as Cu-As, Cu-Sn, Cu-Sb, and Cu-Ni were evaluated photometrical by using the CIELAB color system to serve as a comparison database to evaluate the original metal colour of prehistoric metal objects via their alloy composition, and without destroying their surface through direct measurements (Objective 1B)
4. From different ingots with the composition relevant for archaeology (1, 2, 3, 4, and 5 wt.% arsenic), as well as the 10 wt.% As ingot, a number of specimens were taken and submitted to different thermomechanical histories in order to compare how these are affecting the microstructural features and, consequently, the mechanical properties (hardness; HV measurements) (Objective 1B).
5. Microstructural features of the experimentally produced ingots were compared with those typical of the original Chalcolithic and Bronze Age artefacts, and formation and occurrence of inverse segregation in prehistoric arsenical bronzes detected (Objective 1C).
6. The loss of arsenic was quantified and evaluated as it occurred during prehistoric manufacturing processes through re-melting, casting and annealing activities. Analyses were carried out with DTA, TGA, SEM-EDXS, Mass-spectrometry (Objective 2).
ADDITIONAL WORK:
1. Bronze Age daggers from the Caucasus (Georgia and Russia), made of arsenical bronze, were studied metallographically and chemically (SEM-EDXS, XRF). Also, the lead isotope signature was studied (HR-MC-ICP-MS).
2. In cooperation with the Marie Sklodowska-Curie Individual Fellowship “Breaking the Mould”, UCD School of Archaeology, Dublin (Barry Molloy), material evidence for the production of bronze objects in Bronze Age Europe was evaluated. A specific intention was to disaggregate the various steps in the lifecycle or functional biography of objects with the objective of assessing the potential ways that people could be involved in different varied aspects of the production cycle.
