Metallography on a sickle fragment from the Drassburg/Burgenland hoard find

Abstract

The Drassburg Bronze Age hoard find (approx. 25 kg) also comprises some sickles and sickle fragments. One of these sickle fragments was provided for metallographic examinations. A XRF analysis revealed 94.5 wt.% Cu, 4.31 wt.% Sn, 0.61 wt.% Pb, and 0.12 wt.% S in the alloy. It can therefore be attributed to tin bronzes. The material has a uniform dendritic microstructure. Higher concentrations of Sn, S, and Pb were measured in the interdendritic areas. This suggests a precipitation of the phases Pb and Cu2S from the residual melt. Klemm II etching also revealed the dendritic areas which exhibited different orientations. Deformations were observed in thin edge areas of the sickle fragments. They were introduced in the course of mechanical postprocessing of the bronze or during its use. The surface of the sickle exhibits a patina with a layered structure and a thickness of up to 500 μm. The Sn contents measured in the outer layers are somewhat higher than in the inner layers.