Casting Simulations of Arsenical Copper: New Insights into Prehistoric Metal Production and Materials

Abstract

Abstract To improve our understanding of prehistoric casting methods and materials, simulations for copper arsenic (As-Cu) alloys with up to 15 wt.% As were calculated. Cooling curves and the secondary dendritic arm spacings (SDAS) for the alloy were plotted and calculated, respectively, under non-steady-state conditions with a time-stepping procedure for prehistoric mold materials (e.g., quartz sand, sandstone, terracotta, and steatite). The cooling and microstructure of the alloy was also simulated in iron molds for immediate comparison with as-cast microstructure. The microstructure and SDAS of the as-cast alloys were studied and measured in polished samples with a metallographic microscope. The purpose of this research was to improve our ability to retroactively evaluate the influence of mold materials on as-cast microstructures and determine their materials. This article focuses on As-Cu alloy microstructure and SDAS values, and also discusses the phenomenon of “inverse segregation” and its relation to cooling rate and As concentration.