Synchrotron-Based Phase Mapping in Corroded Metals: Insights from Early Copper-Base Artifacts.

Area of Science:

• Materials Science
• Archaeometry
• Conservation Science

Background:

• Traditional analysis of ancient metal artifacts relies on invasive cross-sectioning.
• Characterizing elemental and phase distribution often requires light and electron microscopy.
• Noninvasive methods are crucial for preserving delicate historical objects.

Purpose of the Study:

• To demonstrate high-resolution virtual sectioning using synchrotron X-ray microcomputed tomography (CT) for noninvasive 3D analysis of metal artifacts.
• To characterize long-term corrosion processes and mineral phase distribution in early copper artifacts.
• To establish a method for analyzing samples where traditional cross-sectioning is impossible.

Main Methods:

• Utilizing synchrotron X-ray microcomputed tomography for high-resolution virtual sectioning of whole objects.
• Employing polychromatic X-ray illumination for semiquantitative evaluation of attenuation coefficients to identify major and minor phases.
• Applying statistical image processing to detect previously unidentified phases.

Main Results:

• Precise noninvasive 3D description of internal and external mineral phases in whole ancient copper artifacts.
• Identification of major and minor corrosion phases and previously unknown phases through CT analysis.
• Demonstrated correlation between CT-identified phases and those found by invasive BSE-SEM, validating the method.
• Observed variations in attenuation coefficients of Cu(I) phases and detailed corrosion stratigraphy.

Conclusions:

• Synchrotron X-ray microcomputed tomography offers a powerful noninvasive tool for studying corrosion in historical metal artifacts.
• The method avoids sample preparation, preserving artifact integrity and allowing analysis of delicate or minute samples.
• This technique provides essential insights into long-term corrosion processes and mineral phase distribution, aiding conservation efforts.