Volume 10, Issue 1, February 2020

Phase diargamm for a system with competing ferromagnetic and antiferromagnetic interactions.

Scanning probe microscopy of the surface of the working portion of the samples after superplasticity deformation at a temperature of 550°C.

Relationship of the t/(K1C/σ0.2)2 and hmax/t criteria for materials in the bcc lattice (dark dots), fcc lattice (light dots) and hcp lattice (combined dots) in CG state (1-4, 7-9, 11, 14) and also in the UFG state (5, 6, 10, 12, 13, 15). The vertical line meets the criterion t/(K1C/σ0.2)2 ≥ 2.5. 1 – С20; 2 – С40; 3 – Fe-0.15C-2Cr-1Mo-1V; 4 – 9MnSi5; 5 – С45 (ECAP); 6 - 9MnSi5 (ECAP); 7 – ENAW-2024; 8 – Fe-0.03C-13Cr-0.1N-19Mn; 9 – ENAW-2618A; 10 – ENAW-2618A (ECAP); 11 – Ti-6Al-4V; 12 – Ti-6Al-4V (ECAP); 13 – Ti-6Al-4V (ECAP + IS); 14 – Ti-6Al-4Mo; 15 – Ti-6Al-4Mo (HR)

A model of the deformation of a polymer composite material based on the sequential breaking of fibers has been developed.

The deformation structural transition is the transition of the material structure to the state of anomalous plasticity as a result of the combined action of thermal fluctuations, static displacements and dynamic oscillatory displacements of standing sound waves formed on natural resonators in the localization of the deformation of the sample

The paper presents the results of computer simulation using the molecular dynamics method of synthesizing binary Cu-Au nanoclusters by condensation from a gaseous phase. For the analysis, we selected the initial configurations of different chemical composition Cu3Au, Cu-Au, Cu90Au10, Cu60Au40 which were cooled with liquid nitrogen in the condensation process. Accord-ing to the simulation results, a relationship was found between the number of clusters formed at the first stage of synthesis and the percentage of gold atoms in the primary gaseous medium.

The laws governing the development of localization of plastic deformation under the conditions of manifestation of the effect of space-time heterogeneity (Portevin-Le Chatelier effect) are investigated. The deformation diagram of an aluminum alloy, illustrates the multiple fluctuations of the flow stress, which detect qualitatively excellent dynamics in different parts of the deformation curve. Statistical distributions of the intervals between the plastic flow stress fluctuations were analyzed, and two critical points were found that indicate a change in the mechanisms of plastic deformation.

It has been established that under shear deformation during SHS extrusion, the modification of Ti – B – Fe with small additions of nano-sized aluminum nitride powder leads to the refinement of the grain structure of the material. As a result of a decrease in the grain of the main phase, the microhardness of the material increases, on average, by 10%.

Problems of forming the mechanical characteristics of sheet metal from the widely used steel 10G2FB.

Ti-40wt.% Nb alloy in UFG state (structural elements’ average size is 0.28 μm) has multiphase structure, which is represented by β-subgrains, dispersive-strengthened with nanoparticles of nanosized ω-phase, and α-subgrains. Annealing temperature range of 773-973 K is characterized by transformation of alloy’s structure from ultrafingerained state into finegrained, active growth of dispersive-strengthened β-phase’s grains size and significant decrease of microhardness. Transformation occurs according to the α→β scheme.

The effect of hardness on the wear resistance of Ti-Al coatings is exponential, and is consistent with the Arсhard model.

Spherical particles extracted from the brass cathode (a) and the distribution map of elements (iron - (b), copper - (c), zinc - (d)), showing the dominance of iron in the particles

The structure of CaCu3Ti4O12 equivalent circuit reveals three processes possible within the material – reach-through conductivity and two overlapping polarization processes – electronic and dipole relaxation ones. Temperature dependencies of specific conductivity in the Arrhenius scale for CaCu3Ti4O12 samples of different thicknesses are linear and characterized by activation energy of 1.05 eV. Temperature dependencies of electric parameters of samples are at their minimums at T = 350 C, which can be explained by the changed polarization mechanism.

The superelasticity at stress-induced α–γ'-martensitic transformation at room temperature in compression was 6.2 % and 5 % in [001]-oriented Fe43.5Mn34Al15Ni7.5 (at. %) single crystals and Fe42.5Mn34Al15Ni7.5Ti1 (at.%) oligocrystals, respectively. Single crystals exhibited good stability of superelasticity in isothermal loading/unloading cycles, in contrast to oligocrystals.

Solid solution «amorphisation» is observed at heating in the temperature range corresponding to α-γ transformation (920-960°C). Amorphous-like material state is retained both at subsequent heating (to 1060 °C) and cooling (to 20 °С), which is super-stable compared to the established metallic glasses.

Presence of vacancy edge defect can be detected by the intense 2D band in the Raman spectrum

Grain size does not affect the diffusible hydrogen concentration in both pure magnesium and the alloy MA14.

Fine-grained (top figures) and ultrafine-grained (bottom figures) microstructure of superalloy EP741NP after superplastic deformation.

The graphs of the dependences of heat resistance on the Larson-Miller parameter have the form characteristic of all the alloys studied, but for each melting composition there are individual characteristics. The calculated and experimental values of heat resistance have satisfactory convergence.

With a free upsetting of the Cu-0.6Cr alloy by ≈90% (е≈2.0), a decrease in the cooling rate of the material leads to an increase in the fraction of mid-angle boundaries and a decrease in the fraction of high-angle boundaries, primarily due to a decrease in the number of twin boundaries.