The paper presents the results of investigation of the magnetization and magnetization reversal processes of sintered Nd–Fe–B type permanent magnets and nanocrystalline anisotropic MQA powder. It is shown how microstructure features determine the processes of magnetization from the thermally demagnetized state and magnetization reversal. The approaches to establishing the prevailing mechanism for the formation of hysteresis properties in permanent magnets based on the estimating of the reversible contribution to the magnetization change Δσ(H) = σ(H) – σr(H) and reversal susceptibility in different magnetic states are presented. The anomalous field dependence of the magnetization constructed based on minor hysteresis loops is demonstrated and explained. Using complementary methods, it is shown that the mechanism of magnetization reversal processes in permanent magnets based on the Nd2Fe14B phase is more complicated than that predicted by models of purely nucleation or pinning.
Abstract—The possibilities of confocal laser scanning microscopy (CLSM) methods for estimating the parameters of crevice and pitting corrosion of austenitic chromium–nickel AISI 316L steel after corrosion tests in aqueous media with various chlorine ion contents are estimated. Saturated and diluted artificial seawater with various chlorine ion contents in the range from 100 to 29 000 ppm is used as a corrosive medium, and the corrosion test time ranges from 1000 to 4200 h at temperatures of 25 and 70°C. Corrosion tests and CLSM studies have found that the foci of crevice corrosion form at a chlorine ion content of more than 7300 ppm in water at both test temperatures and all exposure times, and the formation of corrosion sites with metastable pittings is only detected after the maximum test time at 70°C and the maximum Cl– content of 29 000 ppm.
This paper presents a comprehensive numerical study on size effects and the application of mini-compact tension (mini-CT, or MCT) specimens within the Master Curve methodology for determining fracture toughness, particularly in irradiated nuclear materials. This study, conducted as part of the FRACTESUS project, involves collaboration among several European laboratories to estimate the efficacy of mini-CT specimens through extensive finite element modelling (FEM) and inter-laboratory simulations. The research addresses critical factors, including the consistency of FEM codes, the impact of crack length on displacement conversion factors, and the application of the Beremin model for brittle fracture analysis. The good consistency between the results obtained by the different laboratories validates the numerical approach. The comparison of the macroscopic and local mechanical fields between 1T-CT and MCT specimens highlights the in- and out-plane loss of constraint and the deterioration in the plane strain state in MCT, resulting in the apparent fracture toughness shift on the measured T0 value. The numerical analysis of this shift using the Beremin model show that: (i) numerical simulations can accurately replicate experimental results obtained with MCT specimens, (ii)a size effect is observed on the Beremin fracture parameters, (iii) the use of cross-parameter sets between geometries does not yield satisfactory results, and (iv) the T0 value, using the same parameters for both specimen geometries, is lower is the MCT compared to 1T-CT suggesting that MCT can lead to non-conservative results with respect to 1T-CT.
The solvation state of cations during charge transfer in electrolytes represents a fundamental challenge in hydrochemistry, aqueous batteries, electrocatalysis, electrolytic hydrogen production, and anodic corrosion processes, involving intricate coupling between electronic excitation and solvation dynamics. Although substantial experimental progress has been made, the charge transfer behavior and comprehensive kinetics of metal cations remain elusive. Here, titanium is selected as a model system due to its stable intermediate-valence Ti3+ species with well-defined ion pairs and solvation structures. By integrating ab initio molecular dynamics (AIMD) and synchrotron radiation techniques, we visualize the excited-electron transfer process from Ti0/Ti3+ to solvent molecules, resolving the coupled dynamics of structural evolution, electronic behavior, and solvation reorganization. The radial distribution functions and coordination numbers derived from simulations show excellent agreement with experimental observations, validating the charge-transfer-to-solvent (CTTS) states. The Ti3+ intermediate exhibits stronger ion-dipole interactions, a denser and more symmetric first hydration shell, and a robust hydrogen-bond network that enhances interfacial stability. In contrast, the ground-state Ti0 displays weaker electrostatic interactions and transient hydrogen-bond disruption following excitation. The charge transfer process in both Ti0 and Ti3+ hydration states proceeds through a three-stage ultrafast dynamical evolution over a femtosecond time scale, consisting of excitation, structural reorganization, and hydrogen-bond-network-mediated charge transfer, critically dependent on the spatial coordination between the titanium center and the excited electron.
The prospect of creation of the accumulator of energy on the basis of nuclear isomer 186mRe (a half-life of 2 × 105 yr) does actual a question of the choice of conditions of natural rhenium irradiation by reactor neutrons for production of big amounts of the isomer. Calculations of dependence of the isomeric ratio, known in literature, at formation of 186Re nuclei in ground and isomeric states show insignificant difference in efficiency of production of isomer by thermal neutrons or in active zone of reactor. This conclusion has been confirmed experimentally with an accuracy up to 20
