Determining of the composition of the metallic core of historical objects from surface XRF spectrometry data

A method for estimating the composition of the metal core in historical and archaeological artifacts using surface X-ray fluorescence (XRF) data is described. The method is based on the combination of fluorescence data recorded at points of the object with different degrees of corrosion exploiting the general phenomenon of demetallation of the less noble components of the metal alloy. A theoretical approach is provided using the Johnson-Mehl-Avrami-Erofeev-Kolmogorov (JMAEK) formalism to describe demetallation. Experimental data for binary Zn-Cu brass and Pb- and Sn-containing brass from Hofkirche in Innsbruck agree satisfactorily with the model.