This paper presents a comprehensive study on the strain-induced martensitic transformation and reversion transformation of the strain-induced martensite in AISI 304 stainless steel using a number of complementary techniques such as dilatometry, calorimetry, magnetometry, and in-situ X-ray diffraction, coupled with high-resolution microstructural transmission Kikuchi diffraction analysis. Tensile deformation was applied at temperatures between room temperature and 213 K (−60 °C) in order to obtain a different volume fraction of strain-induced martensite (up to ~70 pct). The volume fraction of the strain-induced martensite, measured by the magnetometric method, was correlated with the total elongation, hardness, and linear thermal expansion coefficient. The thermal expansion coefficient, as well as the hardness of the strain-induced martensitic phase was evaluated. The in-situ thermal treatment experiments showed unusual changes in the kinetics of the reverse transformation (α′ → γ). The X-ray diffraction analysis revealed that the reverse transformation may be stress assisted—strains inherited from the martensitic transformation may increase its kinetics at the lower annealing temperature range. More importantly, the transmission Kikuchi diffraction measurements showed that the reverse transformation of the strain-induced martensite proceeds through a displacive, diffusionless mechanism, maintaining the Kurdjumov–Sachs crystallographic relationship between the martensite and the reverted austenite. This finding is in contradiction to the results reported by other researchers for a similar alloy composition.

In this work, we report the synthesis method of carbon quantum dots (CDs) using the one-step method for fast and effective metal ion determination. Ascorbic acid was used as an inexpensive and environmentally friendly precursor. High-pressure and high-temperature reactors were used for this purpose. Microscopic characterization revealed the size of CDs was in the range of 2–6 nm and they had an ordered structure. The photoluminescence properties of the CDs depend on the process temperature, and we obtained the highest PL spectra for 6 h of hydrothermal reaction. The maximum emission spectra depend poorly on synthesis time. Further characterization shows that CDs are a good contender for sensing Fe³⁺ in aqueous systems and can detect concentrations up to 0.49 ppm. The emission spectra efficiency was enhanced by up to 200% with synthesis time.

In-situ monazite Th–U–total Pb dating and zircon LA–ICP–MS depth-profiling was applied to metasedimentary rocks from the Vaimok Lens in the Seve Nappe Complex (SNC), Scandinavian Caledonides. Results of monazite Th–U–total Pb dating, coupled with major and trace element mapping of monazite, revealed 603 ± 16 Ma Neoproterozoic cores surrounded by rims that formed at 498 ± 10 Ma. Monazite rim formation was facilitated via dissolution–reprecipitation of Neoproterozoic monazite. The monazite rims record garnet growth as they are depleted in Y₂O₃ with respect to the Neoproterozoic cores. Rims are also characterized by relatively high SrO with respect to the cores. Results of the zircon depth-profiling revealed igneous zircon cores with crystallization ages typical for SNC metasediments. Multiple zircon grains also exhibit rims formed by dissolution–reprecipitation that are defined by enrichment of light rare earth elements, U, Th, P, ± Y, and ± Sr. Rims also have subdued Eu anomalies (Eu/Eu* ≈ 0.6–1.2) with respect to the cores. The age of zircon rim formation was calculated from three metasedimentary rocks: 480 ± 22 Ma; 475 ± 26 Ma; and 479 ± 38 Ma. These results show that both monazite and zircon experienced dissolution–reprecipitation under high-pressure conditions. Caledonian monazite formed coeval with garnet growth during subduction of the Vaimok Lens, whereas zircon rim formation coincided with monazite breakdown to apatite, allanite and clinozoisite during initial exhumation.