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 short-range clustering enhanced by migration of non-equilibrium point defects generated under the high-pressure torsion in Bridgman anvils and ball milling is detected by means of Mossbauer spectroscopy in Fe100-cCrc (c = 12-20.6) binary alloys. The degree of short-range clustering is increased with increasing the temperature of severe plastic deformation. The short-range clustering enhanced by severe plastic deformation is similar to that obtained after the thermal annealing and electron irradiation at close temperatures.

The deformation-enhanced atomic redistribution, i.e., accelerated ordering upon warm (573 K) and disordering upon cold (298 K) high pressure torsion, has been investigated using Mössbauer spectroscopy in the binary invar Fe100 –xNix (x = 34.2–35.5 at %) alloys. Results of deformation-induced ordering and high-energy electron irradiation have been compared.

The dependence of the direction and degree of short-range ordering on the temperature of severe plastic deformation has been determined in the Fe 86.8 Cr 13.2 binary alloy using Mossbauer spectroscopy. The stratification decreases upon cold (80–298 K) deformation and increases upon warm (453–573 K) deformation. The enhancement of stratification during warm deformation is caused by the continuous generation of point defects and their increased mobility.

Methods of Mössbauer spectroscopy and electron microscopy have been used to study the effect of the severe plastic deformation by high pressure torsion in Bridgman anvils on the dissolution and precipitation of chromium nitrides in the austenitic and ferritic structure of an Fe 71.2 Cr 22.7 Mn 1.3 N 4.8 high-nitrogen steel. It has been found that an alternative process of dynamic aging with the formation of secondary nitrides affects the kinetics of the dissolution of chromium nitrides. The dynamic aging of ferrite is activated with an increase in the deformation temperature from 80 to 573 K.

Using transmission electron microscopy, X-ray diffraction analysis, Mössbauer spectroscopy, microdurometry, and microindentation, the effect of large plastic deformations (through shear under pressure in Bridgman anvils) on the structure, phase composition, and micromechanical properties of high-nitrogen (1.24 wt % N) 08Kh22GA1.24 steel has been investigated. The steel was obtained by the casting method with counterpressure of nitrogen and was subjected to different heat treatments (quenching from1180°С, aging at 450 and 550°С) that form an austenitic (FCC) structure of the metallic matrix with chromium nitrides. It has been established that deformation by shear under pressure at room temperature results in the dispersion and deformation-induced partial dissolution of primary nitrides Cr 2 N in quenched and aged steel and in the complete (after aging at 450°С) and partial (after aging at 550°С) dissolution of secondary nitrides CrN. It has been noted that, for aged steel that contains finely dispersed secondary chromium nitrides upon shear deformation, as compared to the quenched state, the dispersion of the austenitic structure (down to nano- and submicrocrystalline states) is more intense and the enhancement in the microhardness and resistance to elastic–plastic deformations upon contact loading is more effective.

Разработка высокоазотистых экономнолегированных сталей является одним из перспективных направлений в создании высокопрочных, износо- и коррозионностойких материалов. В настоящей работе исследовано влияние больших пластических деформаций, реализуемых методом сдвига под давлением (СД) при комнатной температуре, на эволюцию структуры (методами электронной просвечивающей микроскопии и рентгеноструктурного анализа) и возможности упрочнения высокоазотистой (1,24 масс. % N) аустенитной стали 08Х22ГА1,24 с исходной α-ОЦК структурой металлической матрицы. Сталь была получена методом литья с противодавлением азота и подвергнута закалке от 1180 °С с последующим высокотемпературным старением при 650 °С продолжительностью 2,5 ч, формирующим ферритную (α-ОЦК) структуру с тонкими протяженными вторичными нитридами хрома Cr2N. Деформация СД состаренной при 650 °С стали с исходной феррито-нитридной структурой приводит к частичному растворению нитридов хрома и формированию наиболее однородной и диспергированной нано- и субмикрокристаллической структуры α-фазы по сравнению со структурами γ+(15–20 об. %)α, сформированными методом СД в состаренной при 550 °С и в закаленной стали с исходной аустенитной структурой матрицы. Измерениями микротвердости по методу восстановленного отпечатка установлено, что деформация СД состаренной при 650 °С стали с перлитоподобной феррито-нитридной структурой приводит к более эффективному упрочнению (до 930 HV0,025), чем у стали с исходной аустенитно-нитридной структурой после закалки, закалки и старения при 550 °С (рост твердости при СД соответственно до 830 и 890 HV0,025). По данным микроиндентирования сталь после отжига при 650 °С и СД обладает также повышенным сопротивлением упруго-пластическому деформированию при контактном механическом нагружении.

The structural and phase transformations and atomic redistribution induced by neutron irradiation have been investigated in aging fcc Fe–Ni alloys using special alloying with elements M (Si, Ti, Al, Zr) that form intermetallic compounds. It has been established that the mechanism and kinetics of disturbance of regions of Ni–M atomic order in atomic displacement cascades upon neutron irradiation are linked to the chemical activity and diffusion mobility of alloying elements. Comparison with the laws of the deformationinduced dissolution of intermetallic compounds has been conducted.

The method of Mössbauer spectroscopy has been used to investigate the effect of the temperature and the rate of megaplastic deformation on the processes of dissolution–precipitation of intermetallic compounds in aging austenitic alloy with a composition of Fe–36Ni–9Al. It has been established that, upon deformation in revolving Bridgman anvils, in the temperature range of cryogenic temperatures (liquid nitrogen) up to 573 K, a change occurs in the character of phase transitions from atomic disordering and the dissolution of intermetallic compounds to their additional accelerated precipitation. The factor that affects the kinetics of the processes of dissolution–precipitation of intermetallic compounds in the metallic matrix is dynamic aging. Dynamic aging is activated with an increase in the temperature and a decrease in the deformation rate.

The deformation-intensified atomic Mn-related separation of the bcc solid solution has been found in Fe100–xMnx alloys (x = 4.5–9.9) subjected to ball milling using Mössbauer spectroscopy. In the near surrounding of iron atoms, the atomic separation is similar to that observed upon the annealing of the alloys in a temperature range of 400–500°С. It has been found that the deformation-intensified atomic separation leads to the stabilization of the bcc phase with regard to the α → γ transformation, as well as to the expansion of the field of the existence of the bcc phase during heating.

Методом твердофазного механического синтеза в шаровой мельнице смеси порошков ОЦК железо-никелевых и железо-марганцевых сплавов с нитридами хрома и последующим отжигом в интервале температур верхней границы -превращения получены наноструктурированные экономно легированные никелем и марганцем дисперсно-упрочненные нитридами аустенитные сплавы.