A heavenly sword – forging a Campo del Cielo meteorite

Abstract

Abstract After a thorough structural examination, a “Campo del Cielo” iron meteorite found in Argentina was forged at temperatures of about 1100 °C. This meteorite is classified as an IA group coarse octahedrite. Besides Fe, it also contains about 7 wt.% Ni and 1.5 wt.% Co, as well as small amounts of Mg, Si, Al, S, and P. Heat treatments above the eutectoid temperature induce a α-γ transformation of the present (Fe,Ni) solid solution. Owing to the retransformation that takes place upon cooling, the typical microstructure of the meteorite vanishes and a mainly ferritic polycrystalline microstructure forms (kamacite α-(Fe,Ni)). Only minor changes could be observed for the initially present taenite γ-(Fe,Ni). Schreibersite, also referred to as rhabdite (Fe,Ni)3P, melts and dissolves into the surrounding matrix. At high temperatures, locally present graphite likewise dissolves and cementite or martensite are formed upon cooling. Changes of other phases such as troilite (FeS) or lawrencite (Fe,Ni)Cl2 could not be detected. Given an initial weight of the meteorite fragment of approx. 1.5 kg, the intention was to manufacture a sword. However, since the meteorite broke apart during forging, only a knife could be manufactured.