Using high energy X-ray imaging to reveal the internal structure of bronze-hilted Iron swords

• High-energy X-rays provide high-resolution tomography of bronze-hilted iron swords. • Complex, varied internal structures specific to each pommel type are apparent. • Variations on the inside may reflect differences in bronze-casting techniques. • The inside reveals limitations in metalworking and complementary techniques. • High-energy X-ray imaging contributes to studies of early Iron Age artifacts. Bronze-hilted iron swords excavated from northern Iran to the South Caucasus are considered the earliest iron tools discovered in these regions. These swords are important for understanding the adoption of iron in these regions, partly because of the possibility that the iron tangs remain inside the hilts without rusting. However, the details of the iron tangs and production techniques, including the method for combining iron and bronze, remain unclear. It is necessary to examine the internal structure of the bronze hilts. Tomography imaging has been attempted, but no concrete findings were achieved. This study utilized high-resolution X-ray imaging techniques, including three-dimensional Computed Tomography, to analyze the internal structure of bronze-hilted iron swords. This enabled the identification of the unique features of their internal structures, which appeared to differ according to pommel type. These techniques illuminated the limitations of early iron metalworking, the techniques used for bronze casting, and the trial-and-error process involved in these developments. These results indicate the efficacy of these imaging methods and suggest fruitful directions for further research on similar archaeological materials.