Low-background gamma spectrometry and neutron diffraction in the study of stony meteorites.

Non-destructive characterisation of meteorites is here performed on a stony meteorite. The identification of the sample is performed by low-background γ-ray spectrometry in order to determine the presence of certain cosmogenic radionuclides, whereas a mineralogical phase quantitative analysis is carried out by Time-of-Flight Neutron Diffraction (ToF-ND) on the sample as-it-is. The protocol is then validated by applying micro-Raman Spectroscopy (µRS) and Energy Dispersive X-ray Spectroscopy (EDS). This paper is focused on γ-ray spectrometry, proving the meteoric origin of the sample, and it also presents some preliminary results of ToF-ND.

Microstructure and phase composition of bronze Montefortino helmets discovered Mediterranean seabed to explain an unusual corrosion.

Two Monterfortino helmets, recovered in the Mediterranean seabed, show unusual features with respect to the more common helmets of the same period and found in underwater environments. Hence, they were investigated by a multi-analytical approach, which allowed us to identify the compounds constituting the helmets and to make some considerations about their metallurgy, although all the metal was converted to degradation products. The helmets, originally made in bronze, have maintained their original shape because of copper sulphides formation. The observed differences in composition between the two helmets were attributed to the position modification, of one of them, into the seabed along centuries. For the first time, a microstructural investigation permits to reconstruct the history of the aging processes involved in the total oxidation of roman bronze helmet metal.

Orthodontic archwire composition and phase analyses by neutron spectroscopy.

Quantitative metallurgical and phase analyses employing neutron diffraction technique were conducted on two as-received commercial rectangular austenitic stainless steel orthodontic archwires, G&H and Azdent, 0.43×0.64 mm (0.017×0.025 inch). Results showed a bi-phase structure containing martensitic phase (45.67% for G&H and 6.62% for Azdent) in addition to the expected metastable austenite. The former may be a strain-induced phase-transformation arising during the cold working process of wire fabrication. Further neutron resonance capture analysis determinations provided atomic and isotopic compositions, including alloying elements in each sample, complementary to the results of traditional energy dispersive X-ray spectroscopy. Together, these results assist in relating commercial alloying recipes and processing histories with mechanical performance, strength and ductility in particular.