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Urartian bronze armours and harnesses in the Reza Abbasi Museum, which had been previously analysed by PIXE (Particle Induced X-ray Emission), have been studied once again in order to obtain additional information concerning metallurgy of the time. For a better understanding of Urartian metalworking, all of these ten items have been studied with a metallographic microscope. The study determined that Urartian metalworkers were experimentally familiar with certain physical properties of the elements. These known properties include the flexibility and approximate melting points of the metals. The forms of the twinnings and slip bands reveal that all of the alloys underwent annealing and forging treatments. After heating to at least 650 ̊C, hot-forging and cold-forging was carried out, depending on the form, usage and importance of the artefacts. After these steps, final annealing was carried out on the alloys. IANSA 2013 ● IV/1 ● 1–1 Poorya Kashani, Bita Sodaei, Shahram Heydarabadian, Behrooz Paranj: A Study of Urartian Metallurgy Techniques Case Study: Urartian Bronze Weaponry in the Reza Abbasi Museum 14 concluded that these samples are low-tin bronzes. The high amounts of copper and tin indicate that these two had been extracted separately from chalcopyrite and cassiterite and melted together. The variation in the Sn amounts illustrates that the ratio of Sn to Cu had been determined experimentally by Urartian metalworkers (Kashani et al. 2013). In this study, for a better understanding of Urartian alloy production processes, metallographic examinations have been conducted on the artefacts in order to investigate the microstructure of these Cu-Sn alloys. 2. Sample preparation The samples were obtained by scalpel from the metal cores in the damaged and marginal parts of the objects. Further operations were carried out in the metallurgical laboratory of Islamic Azad University, Science and Research Branch. Due to the high flexibility of copper and also to protect the metal microstructures, cold mounting was conducted in epoxy (Geels 2007). The diameters of the moulds were 1 cm. Surface mechanical preparation of the metallographic specimens was consequently carried out with various methods of grinding, polishing and etching. The mounted specimens were wet ground with abrasive papers with a 400 Mesh which was gradually increased to 1,200, to reveal the metal surface. In order to produce a smooth surface, the abrasive papers were applied horizontally and vertically intermittently. The specimens were consequently mechanically polished with metallographic wet polishing equipment. The wet polishing was performed with the presence of Al2O3. The last step prior to the microscopic examination was the etching. The metallographic etching is the process of revealing microstructural details which would otherwise not be evident on the as-polished sample. There are three ways for etching: chemical etching, electrolytic etching and heat tinting. Chemical etching is the most common etching method for specimens which are not corrosion-resistant (Scott 1991). Therefore, in this case, the etching operation was applied chemically with a solution of FeCl3 (2.5 g), HCl (2 ml) and C2H5OH (50 ml). 3. Results and discussion Metallographic techniques are used to study the components and physical structures of ceramics, metals and alloy polished sections with the use of a microscope which reflects light passing through the objective lens onto the specimen surface (Scott 1991). In this study, metallographic analyses were observed and compared at 500X. First, the properties of the two main elements, Cu and Sn (Table 1), were introduced. Copper has a Face-Centered Cubic (FCC) lattice structure while the tin lattice structure is Body-Centered Tetragonal (BCT). Metals with FCC structures can be mechanically deformed, drawn out into wire, and hammered into sheets. The melting point for copper is 1,084.62°C while that of tin is 231.93°C. Therefore, where rates of Sn increase, the melting point of bronze alloys decreases. According to Figure 1, the melting point for 10% Sn and 90% Cu is approximately 900°C, although alloys in hot-working should be heated to near red Table 1. Element composition of selected copper-based Urartian bronze artefacts, Reza Abbasi Museum (Kashani et al. 2013). Others Sn (%) Cu (%) Fe (%) Ti (%) Object Code Row – 10.10 89.75 0.15 – 138–139 1 – 3.85 95.74 0.34 0.07 788 2 – 7.57 91.88 0.55 – 789 3 – 9.24 90.02 0.74 – 791 4 Mn: 0.51% 15.73 82.00 1.55 0.21 134 5 – 7.70 90.76 1.45 0.09 799 6 – 7.01 91.55 1.35 0.09 796 7 – 12.17 87.69 0.14 – 137 8 – 6.15 91.38 2.29 0.18 792 9 Zn: 0.49% 13.11 86.31 0.09 – 148 10 Figure 1. Phase diagram of Cu-Sn. IANSA 2013 ● IV/1 ● 1–1 Poorya Kashani, Bita Sodaei, Shahram Heydarabadian, Behrooz Paranj: A Study of Urartian Metallurgy Techniques Case Study: Urartian Bronze Weaponry in the Reza Abbasi Museum