An Erratum to this paper has been published: https://doi.org/10.1134/S0031918X24120019

A sample made from a ribbon of austenitic-martensitic steel 0.3C–13Cr–10Mn–3Si–1V, pre-deformed in the shape of a circular arc with a deflection of 3 mm, was subjected to fast neutron irradiation with a fluence of 6 × 1019 cm–2 in the vertical wet channel of the IVV-2M reactor at a temperature of 80°C. This material belongs to the class of stainless manganese austenitic steels with the shape memory effect (SME). Initially, it was expected that irradiation would reduce the SME magnitude after subsequent heating of the studied sample in comparison with the reference one. But instead, the manifestation of SME was revealed already after irradiation, with a decrease in the deflection by approximately 21

Behavior of the corrosion-resistant EP823 steel (Fe-11Cr-Mn-Mo-Nb-V-W-Ni-Si-0.17C) and its ODS modification, hardened by yttrium, yttrium-titanium oxides (EP823-ODS) in conditions of static mechanical stress under high dose exposure in a fast-neutron reactor was studied using M & ouml;ssbauer spectroscopy and electron microscopy. Mechanical stresses were revealed to result in a deformation of the fuel elements walls and the acceleration of the decomposition processes in steel structure with a release of chromium into the intermetallic chi phase and to the Me23C6 carbide formation. It was also shown that the key factor accelerating the structure decomposition upon neutron irradiation to a dose of 85 dpa at 505 degrees C is anisotropy of stresses between longitudinal and transverse directions of fuel cladding tube surface.

The phase composition of metallic α-U and Fe after mechanical synthesis in conditions of severe (mega) plastic deformation at room temperature using rotational Bridgman anvils was studied using Mössbauer spectroscopy, scanning and transmission electron microscopy. It was shown that mechanical synthesis results in U6Fe and UFe2 intermetallic formation with a precursor represented by UFe2(D) and UFe3(D) defective phases and a defective dispersed mechanical mixture of iron and uranium. Low-level annealing at 300 °C results in the ordering of the defective phases and transition of a dispersed mechanical mixture of iron and uranium into U6Fe and UFe2 intermetallics. The diffusion mechanism of intermetallic formation in conditions of cold deformation of iron and uranium mixture was established, and the high deformation and thermal phase stability of intermetallics U6Fe and UFe2 was shown.

The structure and mechanical properties of new dispersion-hardened Mn-(Cr)-Si-V-C steels with a shape memory effect (SME), which undergo strengthening due to the precipitation of VC carbides in a steel matrix, were analyzed. The stabilizing and the destabilizing carbide aging at different temperatures allows one to control and thus adjust the desired strength characteristics (σ0,2 = 250–880 MPa) and amount of reversible deformation (up to 2.7%). The recovery of the shape of the samples was carried out as a result of both the γ-ε transition in the course of heating after preliminary deformation in the initial austenitic state (i.e., due to the transformation of the γ to the ε phase) and the shear re-twinning of martensite in the martensitic ε phase (i.e., due to the occurrence of transformation of the ε to the twinned εtw phase).

The authors studied radiation-induced structural-phase transformations that had occurred in EP823 steel of industrial application under conditions of its high-dose neutron irradiation in a fast fission reactor. The method of transmission Mossbauer spectroscopy with resonance detection and transmission electron microscopy was utilized. It has been observed that in ferritic-martensitic steel, under the neutron irradi-ation with doses above 50 dpa at temperatures of 570-660 degrees C, the decomposition of a BCC solid solution together with the release of the alloying elements chromium, molybdenum, and carbon from the metal matrix occurs. It is accompanied by the formation of an intermetallic x phase and carbides of the Me23 C 6 type. The authors revealed the formation of the vacancy-clustered and supposedly gas-filled pores in the structure after irradiation. (c) 2021 Elsevier B.V. All rights reserved.

Mössbauer spectroscopy and electron microscopy study of the active redistribution of Ni atoms during the process of polymorphous transformation α→γ in the metastable FeNi31.1 alloy revealed that slow heating (at the rate of 0.2 K/min) results in the depletion of the initial α-phase with a beneficiation of developing disperse γ-phase plates according to the equilibrium diagram. A regulation possibility of the concentration heterogeneity and austenite thermal expansion coefficient resulted from the polymorphous transformation α→γ was shown. Comparison with data of FeNi35 alloy irradiation by high-energy electrons responsible for the variation of atomic distribution and thermal expansion coefficient (owing to the spinodal decomposition) was performed.

In this paper, the energy of the Bain path in Al and the instability of phonons during uniaxial compression deformation along <001> are studied ab initio. It is shown that, at a strain of about 15%, dynamic loss of structure stability is observed due to short-wavelength phonons, which thus determine the theoretical strength of Al. Deformation causes shifts along the {111} planes of the initial fcc cell, leading to the formation of stacking faults. A similar formation of stacking faults was observed in [1] in the framework of simulation of compression along the <001> Ni3Al nanoparticle (L12 superstructure based on the fcc structure). The results obtained can be applied to situations in the experiment, when small defect-free regions are deformed, for example, as in nanostructured materials and during nanoindentation.

Using the Mössbauer spectroscopy and transmission electron microscopy (TEM) methods, the temperature boundary of a strain-induced transformation with the inversion of the direction of nitrogen redistribution is determined in the structure of the FeMn 22 Cr 18 N 0.83 austenitic steel. Deformation by high pressure torsion in Bridgman anvils below the temperature limit (298 K) leads to an increase in the amount of nitrogen in the interstitial solid solution and deformation above the limit (373 K) leads to a decrease in this value. An increase in the deformation temperature leads to the complete dissolution of the products of cellular decomposition and the formation of submicrocrystalline austenite with secondary nanocrystalline nitrides. Changes in the direction of nitrogen redistribution are explained by the competition between the mechanisms of relaxation of the structure along the paths of dispersion, dissolution of nitrides by dislocation, and decomposition of a solid solution supersaturated with nitrogen.

The features of structural-phase transformations during cold rolling and shock-wave loading at (-129...20 degrees C) in austenitic nitrogen-containing steel 0.4N-20Sg-6Ni-11Mn-2Mo-V-Nb are studied. The possibility of the formation of epsilon-martensite with a density lower than that of the initial gamma-phase mainly at high shock loading rates (448 and 471 m/s) is shown. Cold rolling at 20 degrees C does not cause a gamma -> epsilon martensitic transformation. A small amount of martensitic alpha and epsilon phases (less than 5 %) is formed during rolling only at a cryogenic temperature of 196 degrees C. During the shock-wave impact at -129 degrees C at a speed of 448 m/s, plates of epsilon-martensite are formed and preserved. The martensitic orientation relation (111)(gamma) vertical bar vertical bar (0001)(epsilon), [10 (1) over bar](gamma) vertical bar vertical bar [11 (2) over bar0](epsilon) exists between the crystals of the gamma and epsilon phases. The martensitic epsilon-phase formed under low-temperature (-129 degrees C) explosive loading is preserved in the structure, since the observed deformation heating of the metal does not exceed the temperature range of the reverse martensitic transformation epsilon -> gamma (200 - 300 degrees C). Shock-wave loading of steel at 20 degrees C at a speed of 471 m/s leads not only to the formation of the epsilon-phase, but also causes the reverse epsilon -> gamma transformation in those areas that are heated to 250 - 300 degrees C. Shock-wave loading at a speed of 471 m/s at 20 degrees C contributes to the development of cyclic gamma -> epsilon -> gamma transformation, which may be the cause of the phase hardening of austenite and the manifestation of the shape memory effect. In place of the epsilon-martensite crystals, banded clusters of dislocations with a density of 8 x10(10) cm(-2) are formed, corresponding in shape to the location of the transformed martensite plates. In this paper, the high density of dislocations in phase-hardened austenite is associated with the inheritance of the dislocation structure by austenite from the strongly deformed epsilon-phase.

Crowdions in metals are very mobile (compared to others) point defects, providing mass transfer, which is especially important at room and lower temperatures. In this work, the behavior of a crowdion in an fcc metal (e.g., nickel and copper) subjected to severe deformation is studied theoretically. It is shown that, at a certain strain, the 〈110〉 crowdion configuration of an interstitial atom becomes preferable to the dumbbell configuration in a wide temperature range. The atomic displacement fields of a crowdion are described in the Frenkel–Kontorova model. The phonon density of states is found by the molecular dynamics method using Green’s functions. The average velocity of the crowdion motion as a function of the strain rate is found. It is shown that the velocity of the crowdion motion is significantly lower than the velocity corresponding to the maximum frequency in the phonon density of states and decreases with a decrease in the strain rate, which makes it possible to reveal the character of the crowdion motion.

Conditions for the formation of microconcentration inhomogeneities in Fe–Ni alloys, which can decrease their invar characteristics, are determined. The nickel separation can be reached in the course of short-term annealing as a result of deformation-induced nickel segregation, nickel redistribution between martensite and austenite and between ferrite and austenite as well.

A narrow temperature range of changes in the mechanism and kinetics of structural-phase transformations during mechanical alloying under deformation in rotating Bridgman anvils was determined by the methods of Mössbauer spectroscopy, electron microscopy, and mechanical tests in the high-nitrogen chromium-manganese steel FeMn22Cr18N0.83. The experimentally established temperature region is characterized by a change in the direction of nitrogen redistribution-from an increase in the N content in the metal matrix during cold deformation to a decrease with an increase in the temperature and degree of severe plastic deformation. The change in the direction of nitrogen redistribution is due to the acceleration of the decomposition of a nitrogen-supersaturated solid solution of austenite with the formation of secondary nanocrystalline nitrides. The presence of a transition region for the mechanism of structural-phase transitions is manifested in the abnormal behavior of the mechanical properties of steel.

The effect of 15-keV Ar+ ions on the structure of austenitic chromium-nickel steel in the 3.1 × 1017–7.5 × 1017 cm–2 fluence range has been investigated in this work. X-ray diffraction analysis indicates a nonmonotonous change in the lattice parameter and the level of microstresses in some crystallographic directions with increasing fluence. The anisotropy appearance of these stresses gradually decreases and the texture becomes weaker. These processes are associated with radiation defects at the initial stage of irradiation and their radiation-induced annealing as the fluence increases. Transmission electron microscopy has revealed atomic separation in the solid solution and a decrease in the dislocation density in the steel starting from a fluence of 5 × 1017 cm–2 (40 dpa). Similar data have been obtained when steel of a similar composition has been exposed to high-energy ions. No pore formation has been detected under the used irradiation conditions, since the swelling threshold (according to known estimates, ~70 dpa) has not been reached.

The authors present the results of an investigation in Fe-Ni-Cr austenitic alloys of the low-temperature deformation-induced segregations of nickel that form in the micro regions being (i) located close to grain- and subgrain boundaries and (ii) characteristic of the concentration and magnetic inhomogeneities indicated by the appearance of a dark diffraction contrast at the electron diffraction patterns taken from these regions typical (at the same time) of an enhanced value of Curie temperature. The observed effects were connected with the micro distortions caused by the local change of lattice parameter because of an increase in nickel concentration, as well as in the result of a magnetostriction dilatation. Using methods of the X-ray energy dispersive spectroscopy (XEDS) and atomic-probe body-section radiography (tomography - APT) has made it possible to determine the borders of those regions of austenite that were characteristic of an enhanced concentration of nickel in the fields of the localisation of a deformation-induced segregation of nickel in the vicinity of grain (subgrain) boundaries of austenitic alloys of the types Fe-13Cr-30Ni and Fe-37Ni-3Ti.