Filomena Salvemini

Residual stress limits dimensional accuracy and service performance in the Laser-based Directed Energy Deposition (DED-LB) of 316L stainless steel. Process-integrated mitigation was demonstrated using off-axis (oblique-incidence) laser delivery. A 20 mm-thick multilayer build was characterized by neutron diffraction, neutron tomography, electron backscatter diffraction (EBSD), and Vickers macrohardness mapping. Residual stresses were confined to ±100 MPa, with interior tension and surface-adjacent compression; neutron tomography measured ∼0.001% porosity for pores ≥50 μm. Hardness of 150–230 HV20 colocated with compressive zones, and EBSD showed elongated columnar grains with position-dependent texture. The reduced stress state is attributed to the enlarged projected footprint and lower peak irradiance of off-axis delivery, which spread heat laterally, reduce the thermal gradient (G) and cooling rate (T˙), and favor conduction-mode melting. These results establish off-axis DED-LB as a route to in situ residual-stress control and microstructural tailoring while maintaining negligible resolved porosity in additively manufactured 316L components. The bulk, through-thickness maps and datasets provide component-scale validation to calibrate models and support process qualification.

Real-time monitoring of PEG-phosphate phase separation under shear in a vortex fluidic device reveals shear-induced changes in PEG coil structure, with significant implications for biphasic purification processes.

This work involved the use of neutron imaging for the study of the mechanism and rate of capillary water uptake within alkali-activated materials (geopolymers) synthesized starting from natural and industrial waste precursors of the Sicilian territory, to be applied to the conservation of cultural heritage. In detail, the materials were produced starting from Mt. Etna Volcanic ash, basalt cutting sludges and industrial ceramic tiles wastes; the starting formulations were also enriched with different types of additives (calcium-rich or reinforcing fibres); furthermore, all the samples were investigated both as such and after preliminary weathering treatment inducing sodium chloride crystallization. The aqueous solutions transfer capability of the products was investigated, with important implications in the possible formation of efflorescence. This is vital when prospecting a conservation intervention and evaluating the suitability of the materials for this scope. The study during water uptake was conducted by means of neutron radiography continuously acquiring images integrated on 10 s, while the wet samples of the ceramic-based geopolymers group were studied also by means of neutron tomography with the aim of observing the porous structures/the formed fractures in 3 dimensions. The data were treated and the sorptivity of the materials was obtained, giving some indications about the advisable formulations (e.g. with calcium-based additive) and those to be avoided for cultural heritage conservation (e.g. ceramic-based without additive).

Antique swords from the pre-colonial West African kingdom of Dahomey are aesthetically unique, but they also have many design features inspired by swords from Europe, the Islamic world and elsewhere. As the kingdom was famous for importing luxury European objects, this study aimed to pinpoint evidence of Dahomean sword composition and manufacture to determine scientifically whether they were being made in Dahomey, or imported. An inter-disciplinary team made up of historical archaeologists and neutron scientists examined six 19th century Dahomean swords, using a non-invasive multi-methodological approach based on neutron tomography, powder diffraction full pattern analysis and diffraction residual stress measurements. The findings suggest that, despite their foreign design influences, not only were these striking heritage objects made in Africa, they may also have been likely made from locally smelted iron–something that contradicts the assumptions of the few existing historical reports. This has important implications for studies on the kingdom, and also helps to further the long-standing debate surrounding European iron imports—not just within Dahomey, but throughout the wider West African region.

Herein, the effect of heat treatment on the characteristics and properties of cold spray additive manufactured 316L stainless steel employing traditional and a new metal knitting strategy is investigated. 316L feedstock powder characteristics, the geometry of the bulk, microstructure, porosity, microhardness, mechanical isotropy, and residual stress are analyzed in both strategies in as‐sprayed and heat‐treated conditions. Results show that the traditional deposition strategy produced higher mechanical resistance, whereas metal knitting presents a better part geometry accuracy. The heat treatment significantly improves the material strength and the quality of the parts by recovery and recrystallization phenomena. The same microhardness and planar isotropy are achieved after heat treatment of samples produced by both strategies. A discussion about the mechanisms, microstructural, and residual stress evolution is presented.

A bronze wine vessel attributed to 1600–1046 B.C., Shang dynasty in China, an object from the East Asian Collection of the Museum of Applied Arts and Sciences in Sydney (Australia), was studied using a non-destructive scientific analytical protocol based on the synergic combination of nuclear techniques. Gamma spectrometry, neutron-computed tomography, and proton-induced X-ray emission (PIXE) spectroscopy were applied to gain a better insight into the structural and compositional features of the artefact to prove its authenticity. Gamma spectrometry was performed to assess the risk of excessive sample activation induced by long exposure to the neutron beam and to determine the bulk elemental composition. Based on neutron-computed tomography, the porosities and the thickness of the metal wall were evaluated and found consistent with the piece-mould casting technology adopted by craftsmen during the Shang dynasty in China. Finally, PIXE spectroscopy demonstrated the use of a ternary (copper–tin-leaded) alloy and the nature of mineralisation on the surface.