ANALYSIS OF ALLOYS AND CORROSION STRUCTURES IN ANCIENT BRONZES USING THE COMBINED PROTOCOL OF X-RAY FLUORESCENCE AND MONTE CARLO SIMULATION (XRF-MCS)

One of the key aspects to consider when dealing with a cultural asset is its uniqueness, which necessitates its preservation. Therefore, the development and application of nondestructive techniques is indispensable in the field of diagnostics. Among these, X-ray fluorescence (XRF) is one of the most widely used methods for investigating the elemental composition of archaeological objects, such as metal artifacts. However, qualitative elemental analysis alone is often insufficient to fully understand the composition of an alloy and, consequently, the metallurgical knowledge of the society that produced it. Although bronze is a relatively simple alloy, it has a complex microstructure due to the natural corrosion processes that have been formed by the interaction between the surface and the environment. These processes generate heterogeneous multilayer patinas, which can also produce phenomena such as selective enrichments or depletions of specific elements within the alloy. Such alterations pose significant challenges to the accurate characterization of ancient bronze artifacts. To overcome these challenges, an advanced analytical protocol was developed that integrates X-ray fluorescence (XRF) with Monte Carlo simulation (MCS).[1] MCS is a probabilistic algorithm used, in this case, to simulate a real XRF measurement. This approach enables modeling of multilayer corrosion structures, allowing for a more precise quantification of the elemental composition and a deeper understanding of the original alloy’s characteristics. By applying this methodology, we can identify the original alloys of an artifact and variations in composition, due to rework or restoration of the object or alteration processes through characterization of corrosive structures.[2] In addition, a portable XRF instrument was used in these studies, so the analyses were performed directly in situ, without the need to move the artifact. This technique has been successfully applied to many bronze artifacts, including Sardinian-made navicelle and tools, as well as Etruscan fibulas and statuettes. The data obtained using the XRFMCS protocol were also compared with those acquired using destructive techniques, obtaining very similar results, underscoring the method's reliability and potential for applications in the field of cultural heritage conservation and archaeometallurgical studies.[3]