Manufacturing Techniques of Ancient Forged High-tin Bronze Wares from Archaeological Sites in Bagan, Myanmar

Abstract

Bronze wares made with forged high-tin bronze technology were first produced in the Persian region of the Orient, gradually brought to India and then to China and the Korean Peninsula. By scientifically analyzing bronze artifacts of Myanmar, which is located halfway between Persia and Korea, it is possible to confirm the trade and the propagation route of technology at the time. This study scientifically analyzed bronze artifacts excavated from the Bagan ruins in Myanmar to identify the manufacturing technology. Forged high-tin bronze wares in Bagan Dynasty are with alloy compositions Cu-Sn. Composed of Cu-Sn only were manufactured by alloying Cu with Sn in a ratio of 76 wt% and 24 wt%, which is a relatively high tin content. High-tin bronze wares composed of Cu-Sn were manufactured with the bronze material of an alloy of Cu and a large amount of Sn by hot working (forging) and finished by quenching. The microstructure indicates temperatures at which the quenching was performed and various microstructures that occur in different temperature ranges are observed such as β (M), γ phase, δ phase as well as primary crystals, α phase. The presence of different microstrucures suggests multiple high-tin bronze wares were quenched at a wide range of temperatures. The non-metallic inclusions of the bronze wares contain sulfur, which indicates with high possibility that the copper provided as the raw material was extracted from copper ores containing sulfur.