November_December_2021_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | N O V E M B E R / D E C E M B E R 2 0 2 1 2 3 T unisia is a country with a very rich history and loaded with archaeo- ological sites and metallic arti- facts. These can be dated back to ear- ly civilizations that shaped the history of the region, namely the Punic, the Ro- mans, the Byzantines, and the Islamic conquest including the Aghlabids and the Ottomans. Artifacts were found in different archaeological sites and could be retraced back to 300 B.C. An archaeological excavation in Monastir, a city in central-eastern Tu- nisia (Fig. 1) dug out iron-base artifacts that were dated back to the Aghlabid dynasty, who were known for their con- struction work. The artifact targeted in this article is a 18.8 cmnail dated by archaeologists to the 10th century A.D. and found with others near a housing site where wood was substantially used. The dimension suggests that it could have been used for construction. The scope of the metallurgical analysis was to investigate the mor- phology of the nail, its chemistry, micro- structure, and anything that would lead to the understanding of its processing. EXTERNAL AND INTERNAL MORPHOLOGY The artifact had an apparent con- ical shape with a homogenous cor- rosion layer. It was very important to avoid altering the state of the artifact, so destructive testing was not allowed except on a tip that was detached from another nail at the same site (Fig. 2). Visual observations backed by cross-section analysis of a broken tip of a parent nail, revealed that the basic structure of the nail may be pyramidal (Fig. 3a). X-ray radiography (Fig. 4) helped to define the internal structure of the nail (Fig. 5). At the surface, a layer, less dense than the core, was identified. Cross-section observation shows that this layer might be oxidization of about 20% of the surface (Fig. 3b). ARCHAEOMETALLURGICAL STUDY OF AN ANCIENT NORTH AFRICAN IRON-BASE ARTIFACT A metallurgical study of a 10th century iron-base nail from the central-East coast of Tunisia reveals how early metallurgists without modern scientific knowledge created parts with engineered properties. Nihad Ben Salah* NBS-M&P Consulting, Quebec, Canada *Member of ASM International Fig. 1— The Aghlabid dynasty expansion in the Mediterranean Sea (in orange) encompassing Tunisia. Adapted from en.m.wikipedia.org/wiki/Aghlabids. Courtesy of Nanoxyde. Fig. 2 — Apparent shape of the nail and sampling authorized for the study.