Experimental Studies on Alloy Composition and Microstructure of some Bronze Objects from Iron Age Site of Baba Jilan, Luristan

Applications of bronze alloy to produce different decorative and ritual objects have been commonplace during the Iranian Iron Age. A large number of bronze objects from the second and first millennia BC are discovered from archaeological excavations. Many of these objects were found from the Iron Age graveyards and sanctuaries of Luristan region. In this paper, some bronze objects discovered from Baba Jilan Iron Age graveyard, Pish-i Kuh of Luristan, are examined by analytical methods. For this purpose, metallography and SEM-EDS methods are employed to identify alloy composition and microstructure of bronze samples. The results showed that all samples are made of variable tin content bronze alloy. The variable tin content is a common event in Iron Age bronze objects and proves that an uncontrolled alloying method has been used to make bronze alloy. Analysis of different fine phases scattered in the microstructure of samples showed that they are sulphidic inclusions as well as lead globules. On the other hand, metallographic observations revealed that cycles of cold working and annealing are used to shaping and manufacturing the objects.