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Results are presented from analyses that were conducted to explain the presence of chromium, detected noninvasively using energy‐dispersive X‐ray fluorescence (XRF), in the unusually large (2‐3mm diameter) rough gem‐like purple pigment particles in the paint used for a Faiyum mummy portrait. An approximately 50 μm diameter particle of the chromium‐containing purple pigment was extracted from the Portrait of a Bearded Man, dated to Roman Imperial Egypt in the second century, circa 170‐180 CE, accession #32.6 in the Walters Art Museum collection. The particle was characterized using energy‐dispersive X‐ray fluorescence analysis, electron microscopy, diffraction, and atom probe tomography. It is demonstrated that the purple pigment particle is a heterogeneous organic pigment, specifically, a lake pigment likely derived from either plant or insect matter, which contains minor percentages of both transition metals and alkali / alkali earth metals, with nanometer‐scale crystallites of lead carbonates and sulfates. The analyses revealed for the first time the nanoscale microstructure and stratigraphy in an ancient lake pigment. Results suggest that similarities with respect to time period and place of production may be developed among unprovenienced Faiyum mummy portraits to help localize workshops or artists, using analyses focused on lake pigments to characterize specifically metal‐based mordants. [ABSTRACT FROM AUTHOR]

Elemental powder mixture of Fe-14Cr-1Ti-0.3Mo-0.5La2O3 (wt%) composition is mechanically alloyed for different milling durations (5, 10 and 20 h) and subsequently consolidated via spark plasma sintering under vacuum at 950 °C for 7 min. The effects of milling time on the densification behavior and density/microhardness are studied. The sintering activation energy is found to be close to that of grain boundary diffusion. The bimodal grain structure created in the milled and sintered material is found to be a result of milling and not of sintering alone. The oxide particle diameter varies between 2 and 70 nm. Faceted precipitates smaller than 10 nm in diameter are found to be mostly La-Ti-Cr-enriched complex oxides that restrict further recrystallization and related phenomena. [ABSTRACT FROM AUTHOR]