Раздел "Получение и анализ структуры материалов"

Disk-shaped nickel plates processed by high pressure torsion were successfully joined by ultrasonic welding. Welding resulted in the grain growth which is uneven along the cross-sectional height of the welded specimen. The specimens showed a gradient microstructure with a grain size ranging from 3 μm in the lower plate to 6 μm in the upper one, along with a developed substructure, after the process of USW.

Figure shows experimental data on particle growth during isothermal annealing at 1300 °C as a time dependence of the average particle volume. For particles located at different distances from the sample surface, these dependences are approximated by straight lines with close angular coefficients (curves 1 and 2).

The annealing at 700 °C for 50 h leads to noticeable changes of the carbide subsystem of low-activation high manganese austenitic steel. After solution treatment (ST) it causes precipitation of M23C6 particles along the grain boundaries and on the MC particles. Annealing of the cold-rolled (CR) samples leads to the formation of these particles at the microtwin boundaries.

This work shows the influence of the degree of severe deformation on the morphological features of α-phase particles in aged metastable β-titanium alloy Ti-15Mo.

The powder morphology, phase composition and microstructure were thoroughly investigated. The temperature ranges of phase transformations in the powder during heating and cooling have been established

Mechanical alloying of elemental powders and subsequent thermal treatment were applied to synthesize Ti6Co16Si7- and Ti6Ni16Si7- based composites.

Change in microhardness depending on the initial microstructure and processing (thermal cycling and annealings)

Structure and the mechanical behavior of a near-alpha multilayer laminate under impact loading

The powder EP741NP superalloy with the initial ultrafine-grained microstructure after superplastic deformation and a solid-state joint in combination of the EP741NP superalloy and a cast intermetallic VKNA-25 alloy.

The artificial aging did not result in any change in the AK12 alloy's microhardness, whereas T6 treatment led to a uniform increase in microhardness throughout all zones of the sample. There was no significant grain growth observed in the aluminum-based solid solution and silicon particles after these heat treatments.

Structural behavior and hardening of the high-strength aluminum alloy 1965 after isothermal rolling at the temperature of liquid nitrogen with reductions in the range of 30-70% was studied for two pre-quenched conditions - the homogenized ingot and further hot-forged billet. In spite of differences in the initial structure parameters, the structure transformations in both the alloy states under cryorolling were preferably associated with the formation and development of the dislocation-cellular structure of the matrix.

The influence of warm multidirectional isothermal forging on the grain structure and mechanical properties of the high-nitrogen austenitic steel VNS-53-Sh has been studied. It has been shown that the average grain size was reduced to ~ 6 μm after forging compare to initial state due to the formation of small grains at the boundaries of the original grains and fragmentation of them. It promote an increase in strength properties.

Microhardness of the Cu-Al-Cu sample after accumulative HPT before and after annealing (left) and schematic representation of the effect of accumulative HPT and further annealing on the sample (right).

The geometric scheme illustrates changes in size of coordination tetrahedron in ZnSxSe1-x substances diluted by 3d-impurity. Neutron-diffraction characterization of structure instability of ZnSxSe1-x:M (M=3d-ions) solid solutions are presented in the article.

In niobium filaments of the Cu-7.7%Nb composite under cold-drawing beginning from the true strain of 8.5, macrostrains are observed according to the X-ray data, which is confirmed by TEM data, which demonstrate distortions of niobium lattice and formation of partially coherent boundaries (110)Nb || (111)Cu. These macrostrains are anisotropic and higher than those in the Cu-18%Nb composites.

The distribution of microhardness (HV 0.5) and the average amount of γ-, α- and ε-martensite in a sample made of steel Fe-0.02C-18Cr-8Ni after SPDT (a) and the distribution of α-martensite under the ductile static fracture surface of steel after ECAP (b, c)

High-temperature annealing of low-activation chromium-manganese austenitic steel leads to discontinuous precipitation of dispersed M23C6 carbides along grain boundaries, micro- and nanotwin boundaries. At coherent twin boundaries, the growth of particles during annealing is limited by cross-sectional dimensions of the twin plates.

The typical macrostructure of the AK4-1 aluminum alloy with local mixing of the AK12D alloy into it via friction stir processing

The inter-fragment boundary misorientation distributions are close at two temperatures of deformation, except for the high-angle peak associated with the twinning at 0.5Tm (Tm is the melting temperature of copper).

Grain fragmentation in tensile strained copper is orientation dependent

The effect of exposure (30, 60, and 120 min) during the processing in the low-pressure non-self-sustained arc discharge plasma on microstructure and phase composition of the modified surface layers obtained in a Ti-6Al-4V alloy with a preliminary deposited Al coating has been evaluated.

explains the efffects of Ce content on the properties as well as on the formed morphologies and scales.

The paper describes the two-stage modification of the surface layer of Al-20%Si alloy that combines electroexplosive alloying by an Al-Y2O3 system with subsequent irradiation by pulsed electron beam. Study of the structure and properties of the modified layers of the material under study by the methods of modern physical materials science.

The effects of heat input magnitude and adjustment on microstructure and mechanical characteristics of Al-5%Si and Al-12%Si alloys prepared using electron bean wire feed (EBAM ) and wire-arc additive manufacturing (WAAM) have been investigated.

As cast Al-1.8Mn-1.6Cu-0.15Cr-0.15Fe (wt. %) alloy structure consist of aluminum solid solution, eutectic Al6(FeMn) and Al2Cu, as well as Al7Cr and Al20Cu2Mn3 dispersive particles. Radial shear rolling results in partial dissolution of Al20Cu2Mn3 dispersoids, grain refinement to the size of 1.6 μm, increasing yield stress up to 83 MPa and ultimate strength up to 216 MPa. The plasticity of the deformed alloy is 25%.

Nanoporous germanium surface formed by magnetron sputtering and ion implantation

It is shown that necessary the homogenization annealing and subsequent quenching for getting one phase state of Ni44.4Mn36.2Sn14.9Cu4.5 alloy.

Циклические вольтамперограммы, диаграммы Найквиста и СЭМ изображения микроструктур образцов пленок

The structure and properties of AISI 321 steel depends on the level of normal load on the indenter during frictional treatment. Friction treatment with a sliding indenter leads to the formation of a gradient structure with a depth of up to 500 µm.

The effect of combination of isothermal cryorolling at liquid nitrogen temperature to strains ranging from 30 to 90% and subsequent high-dense electropulsing, on the structure and hardness of an initially coarse-grained pure nickel was studied.

Superplastic behavior of nickel-based superalloys with ultrafine grain structure.

Seebeck coefficient S and the power factor Р for the composite оf CuO - 40%, LiCoO2 - 30%, LSMO - 25%, GeO2 - 5%.

Established that at the increase of the mass fraction of carbon from 0.09% to 0.30% in the as-cast metal, the metal hardness increases. At the same time, the structural-phase composition consists of a pseudo-pearlitic structure (ferrite-nitride mixture) and austenitic structure in different ratios since an increase in the carbon content leads to an increase in the amount of the pseudo-pearlite. The heat treatment of specimens with the mass fraction of carbon of 0.09% and 0.30% at 1250 °C for two hours leads to their complete austenization. In this case, the hardness of steels of both compositions decreases to 22 – 24 HRC (0.09 wt.% of carbon) and to 28 – 30 HRC (0.30 wt.% of carbon).

It is shown that with an increase in temperature, load, and holding time, the volume fraction of pores decreases, and the fraction of fiber increases, which leads to an increase in the composite strength. In all cases, the shape of the fracture surface indicates the brittle nature of the composite fracture.

The value of the nitrogen compositional stability coefficient has been determined for the alloys of the Fe-Cr-Mn-Mo-N system obtained by self-propagating synthesis, namely, aluminothermy under nitrogen pressure. The obtained results permit to predict the maximum possible content of nitrogen in continuous ingots (without bubbles and gas porosity in the volume) and, consequently, the structural-phase composition of alloy and optimal regimes of alloying.

Images of samples obtained at a temperature of +5 ° demonstrate a completely different morphology in comparison with samples obtained at +25°, demonstrate a completely different morphology in comparison with samples EDX elemental mapping indicated that the particles contain mainly Cu and O in both samples.

The properties of Cr,Mg-codoped bismuth tantalate pyrochlore have been investigated

Experimental refinement of monophase state regions on the phase diagrams parts of FePt and CoPt alloys

Microstructure of HIP superalloy and after subsequent hot deformation.

HPT at 6 GPa pressure in the range of 0-10 rotations of pre-quenched ingot of the commercial aluminum alloy 1965 resulted in consequential transformation of well-defined dense dislocation wall/cell structure to non-equilibrium nanofragmented one and near two-fold hardenning. The alloy strengthening and/or softening during further natural aging up to 500 hrs were within 10-15% and controlled by simultaneous decomposition of the aluminum solid solution and recovery of its deformation structure.

The process of superplastic forming into a cylindrical matrix of workpieces from the EK61 superalloy with an ultrafine-grained structure has been studied.

Structures of a thin-film high-entropy alloy deposited on steel AISI 321.

Low-heat input friction stir welding/processing of Cu-Cr-Zr alloy produces an ultrafine-grained structure reinforced with Cr and Cu5Zr nanoparticles, resulting in a hardness level of 150-190 HV1.

A ceramic material based on rare-earth zirconates with a pyrochloric structure, possessing phase and structural stability at 1300 °C was obtained. The use of REE oxide concentrate is promising for TBCs with thermal stability above 1200°C.

A cubic perovskite of complex composition Pb1/3Na1/3K1/3Ta2/3Fe1/3O3-δ (sp. gr. Pm-3m, a = 3.9767(3) Å) was synthesized for the first time by the solid-phase reaction method.

Schematic representation of distribution of microhardness over the sample cross section depending on the annealing temperature.

The features and fracture mechanisms of reactor low-activation ferritic-martensitic steel EK-181 after high-temperature thermomechanical treatment and traditional heat treatment are revealed depending on the impact test temperature in the range from -186 to 100°C. The fracture appearance transition temperature is determined by a fractographic investigation.

The influence of warm plastic deformation by rolling at 600 and 900 °C with a total strain of e = 2 on the microstructure and mechanical properties of the reactor austenitic steel EK-164 has been studied. The resulting fragmented banded microstructure with a well-developed substructure and fine grains provides high strength properties.

A new low-activation chromium-manganese austenitic steel for nuclear power engineering with an increased manganese content and additional alloying with strong carbide formers has been fabricated. The new steel has improved strength and ductility properties compared to known analogues.

The single-step (low-temperature) homogenization of the Al alloy 1570C, recommended by the alloy developers, did not lead to the complete removal of chemical heterogeneity arising during crystallization. An additional high-temperature annealing step resulted in some reduction in the alloy strength, but was effective in eliminating the chemical heterogeneity of the cast structure and increasing corrosion resistance while maintaining the grain size and dispersity and coherency of the nanosized Al3(Sc,Zr) dispersoids present in the alloy.