Evolution of High Tin Bronze Technology in Korea as Observed in Bronze Objects of the Unified Silla Period, Excavated from the National Gyongju Museum Site

摘要

Korea is famous for its long history of manufacturing high tin bronze objects of near peritectic composition by the application of forging and rapid cooling at approximately 700 degrees C. Not much is known, however, of the origin and developmental processes of this technique. Fortunately, valuable evidence for assessing the associated technological evolution was found by examining the microstructure and chemistry of bronze objects excavated in the National Gyongju Museum construction. site. Initial awareness of the technique was clearly visible in the selection of unleaded high tin bronze alloys of varying tin levels and the application of special thermo-mechanical treatments involving forging and quenching from the alpha-beta or alpha-gamma phase field of the Cu-Sn system. This observation along with the excavation contexts suggests that the high tin technology was gradually established in Korea by a long period of experimentation, starting from the 8th century AD or earlier.