Characteristic features of metal artifacts excavated in western Yunnan in the Bronze Age

Abstract

Yunnan province is located in Southwest China. A technical study of the metal artifacts unearthed in western Yunnan can not only improve our understanding of the bronze culture but also fill many gaps in the archaeological studies that have been carried out on prehistoric bronzes from Yunnan. In this paper, we summarize the results of our analyses of bronzes dating from the seventeenth century BCE to the second century BCE. Ninety-nine metal artifacts, including weapons, tools, and decorative objects have been analyzed by optical microscopy and scanning electron microscope (SEM) with energy-dispersive spectroscopy (EDS) to examine the microstructure and composition. The results show that a variety of alloys were employed, including unalloyed copper, copper-tin, copper-tin-lead, copper-arsenic, copper-arsenic-lead, copper-lead-antimony, copper-antimony, lead-antimony-arsenic-copper, carburized bloom steel, and hypoeutectoid steel. The copper alloys were fabricated by casting, cold working after casting, and annealing. This study has expanded our knowledge of bronze culture in these areas and reveals some of the technological relationships among the regions of western and central Yunnan, the northern steppe, and Southeast Asia.