The structure of an Fe-32% Ni alloy preliminarily quenched for martensite and subjected to α→ γ transformation upon a slow heating to different temperatures (430–500°C) has been studied by the electron-microscopic method. There has been observed an intermediate ɛ phase with an hcp lattice and rarely encountered Headley-Brooks bcc/fcc orientation relationships, which differ from the Kurdjumov-Sachs relationships. The networks of reflections of the ɛ phase have been observed in electron-diffraction patterns of the Fe-32% Ni alloy after both a slow heating to 430°C without annealing and a slow heating to 500°C with a subsequent annealing at 280°C; the Headley-Brooks relationships between the α matrix and the γ phase, which are typical for increased temperatures of phase transformations, have been observed in the samples after a slow heating to 500°C with annealing.

Metallography and X-ray diffraction analysis were used to study regularities of martensitic transformation in an N31 iron-nickel melt-quenched alloy. The substantial differences in volume fractions of the martensite phase in local regions of thin ribbons of the alloy are related to the size effect of the transformation and structural nonuniformity of the ribbons.

The effect of dispersed oxide phases of Y 2 O 3 -TiO 2 type on the wear rate and the friction coefficient of the high-chromium martensitic 18Kh12V2 and ferritic 01Kh13V2 steels upon sliding friction in pair with the 40Kh12 steel has been studied. The structure of these materials has been analyzed by metallographic and electron-microscopic methods. It has been shown that the presence of about 0.5% dispersed oxide particles, including nanosized ones, in the structure of the ferritic 01Kh13V2 steel exerts a complex influence on the wear resistance of this steel. Upon dry friction under the conditions of adhesive wear, the 01Kh12V2 steel alloyed with oxides is characterized by a low wear resistance. It is caused by an increased brittleness of the steel, which activates the processes of seizure and deep tearing at the friction surface of the steel. In the case of lubricated friction (boundary friction regime), dispersed oxide phases exert a great positive influence on the wear resistance of the steel. The wear rate of the oxide-strengthened ferritic steel in this case is about twice as low as that of the steel nonalloyed with oxides. It is caused by the formation of numerous pores in the surface layer of the alloyed steel in place of spalled oxides. The formation of pores helps better retention of a lubricant in the friction zone (the effect of self-lubrication), which decreases the probability of adhesive inter-action between the contacting steel surfaces. It has been found out that the alloying of a high-chromium martensitic 18Kh12V2 steel with a small amount (∼0.3%) of oxides of the Y 2 O 3 + TiO 2 type does not exert a noticeable influence on the tribological properties of the steel under consideration. The oxide phase does not affect noticeably the magnitude of the friction coefficient of the steels tested.

The N30K10T3 and N40K10T3 invars with the Curie points θC ≈ 200°C and θC ≈ 310°C and the martensite temperatures M s ≈ −80°C and M s < −196°C, respectively, have been studied. The two alloys were hardened by quenching in the range of temperatures from 100 to 750°C. In addition, the first alloy was hardened by a combination treatment including phase-transformation-induced hardening and aging. The method of phase hardening consisted in the use of a forward (γ → α) and a reverse (α → γph) martensitic transformations. It has been shown that the temperature dependences of the linear expansion coefficient and the dependences of the hardness on the temperature and time of aging are considerably different for both alloys upon decomposition of the supersaturated solid solution. Both the ordinary and the double aging have been studied.

The precipitation-hardening manganese austenitic steels with different content of carbide-forming elements and carbon obtained by the method of rapid melt quenching have been considered. The influence of dispersion of the structure on the morphology of carbides, strengthening, and the magnitude of shape-memory effect has been investigated.

We have investigated the influence of multiple γ-α-γ transformations proceeding by the shear mechanism on the structural-phase state of austenite in iron-nickel alloys N28T2Yu2 and N32. It has been shown that it is possible to form, by cyclic γ-α-γ transformations, a fine-grained structure of austenite due to the fragmentation of the initial structure that develops under the conditions of progressing disorientation of the crystal lattice of the γ-phase. In the process of thermocycling, the reversed austenite was continuously strengthened under the condition of the development of disorientation of its lattice.

Local plastic strains, which develop at the initial stages of delayed fracture of the heat-affected zone of high-strength low-alloy 14KhGN2MDAFB steel with σ0.2 ≥ 700 MPa, have been investigated using x-ray diffraction analysis. It has been found that the local plastic strain values increase with time of holding under long-term loading. In this case, the maximum local plastic strain occurs in the vicinity of the fatigue crack tip. The kinetics of the local plastic strain development during thermal cycling is affected by the specimen cooling rate W6/5.

The crystalline structure changes of fresh martensite (FM), formed from the austenite phase in Fe–25.3 wt.% Ni–0.5 wt.% C steel single crystals after successive γ–α–γ transformations, have been studied by X-ray diffraction at low temperatures. Diffusion-mediated redistribution of carbon within the α-crystal lattice and loss of carbon out of it are the driving processes which determine the structural change of FM at cryogenic temperatures. The decomposition of transformation-hardened martensite at low temperatures can be described in terms of coherent stress relaxation and carbon reordering in the crystal lattice.

Single-crystal specimens of 50N25 steel were examined by the X-ray diffraction method to study low-temperature changes in the crystal structure of martensite freshly formed in austenite subject to gamma-alpha-gamma transitions. It was shown that, at cryogenic temperatures, the decomposition of transformation-hardened martensite was superimposed on the relaxation of coherent stresses and the ordering of carbon atoms in the interstices of the crystal lattice.

Conditions of the production of nanocrystalline austenite as a result of γ → a → transformations in metastable austenitic Fe-Ni-based alloys are analyzed. The mechanism of the a → y transformation is investigated at various rates of heating. The formation of nanocrystalline austenite is used to produce alloys with enhanced physicomechanical properties (with a controlled thermal expansion coefficient, high strength, and high magnetic hysteresis properties).

The yield strength of commercial iron subjected to laser treatment is calculated on the basis of experimentally determined characteristics of the structural state of surface layers, The hardening produced by laser melting is shown to be comparable with those of phase-transformation-induced hardening or strain hardening and is mainly related to an increase in the dislocation density and microstructure refinement.

X-ray and magnetometric methods are used to investigate the effect of multiple gamma double left right arrow alpha. transitions on the crystal structure and characteristics of the subsequent martensitic transformations in carbon iron-nickel alloys. It is shown that the effect depends on the heating rate in the range of the reverse alpha --> gamma transitions and is mainly governed by the thermal stability of the carbon gamma -solid solution in relation to decomposition with precipitation of carbon.

Conditions of the production of nanocrystalline austenite as a result of gamma --> alpha --> gamma transformations in metastable austenitic Fe-Ni-based alloys are analyzed. The mechanism of the alpha --> gamma transformation is investigated at various rates of heating. The formation of nanocrystalline austenite is used to produce alloys with enhanced physicomechanical properties (with a controlled thermal expansion coefficient, high strength, and high magnetic hysteresis properties).

By X-ray method was investigated distribution of residual stresses in surface layer carbon steels after ms-pulse laser treatment. The total residual stresses were presented as a sum a) of residual plastic deformations after local thermal influence; b) of bulk effect of structural and phase transformations and c) of processes of saturation of the smelt surface by introduction atoms. With the help of analysis of the structural factors (the dislocations density, the crystal parameter) and mechanical properties were investigated changes of separate components of residual stresses. For steels with 0.08, 0.35 and 0.85 wt.% C was established the correlation between laser treatment modes and character of residual stresses.

The effect of regimes of pulse laser radiation on the formation of the microgeometry of the treated surface of technical iron is considered. The energy density range characterized by the formation of a specific wavy microrelief on the surface of the melt is determined. The variation of its parameters with increase in the radiation energy is studied.

Effect of pulsed laser treatment on the distribution of residual stresses, microhardness, and dislocation density in the plane of treatment was studied in armco iron. It is shown that, depending on the regime of treatment, compressive or tensile stresses can arise across the width of the laser path and that the enhanced microhardness in the zone of laser treatment correlates with the dislocation density in it.

Optical microscopy, transmission electron microscopy, X-ray diffraction, and microhardness measurements were used to study the structure formation in armco iron in the zone of pulsed laser irradiation. In this zone, there: arises either an increased density of dislocations that form a fragmented structure in the initial grains Cat a density of laser irradiation energy below 3 J/mm(2)) or a set of different microstructures (at an energy density of 12-14 J/mm(2)). The variety of microstructures is determined by the specific features of the Fe-C phase diagram and structure formation at high heating rates and high rates of cooling from different temperatures. A correlation between strain hardening and dislocation density in the zone of laser action was established.

Samples of pure cobalt were treated by spark erosion in distilled water and in oil and investigated by X-ray diffraction. After cutting in oil a Co-C fee solid solution and an unidentified phase are formed. Concentration of carbon in the Co-C solid solution and positions and intensity of reflections of the unknown phase are found to have spark energy dependence.

Laser treatment of alpha-Fe single crystals was shown to lead to complex recrystallization of the material with the formation of both polycrystalline and single-crystal structural constituents.