A multilayered hybrid Al1050/AZ31/Al1050 alloy was fabricated by cross-accumulative roll bonding (CARB) up to 5 cycles at 400 °C. Microstructure, anelastic, and mechanical properties were characterized using scanning electron microscopy (SEM), internal friction (IF) measurements, and tensile tests, respectively. The thickness of AZ31 layers of the initial sample gradually loses its continuity in the form of localized necking and fragmentation and reduces to less than 150 µm after the fifth cycle and, contrarily, that of the Al1050 layer increases. Hot CARB processing causes an enhanced formation of intermetallic compounds. For almost all the cycles, apart from N = 1, the ultimate tensile strength of the sandwich measured in the transverse direction is comparable to that of the rolling direction. A maximum value of 182 MPa is achieved after one cycle in the transverse direction and a ductility of 9

Heat-resistant metal alloys designed for high-temperature applications in an oxidizing environment possess the ability to develop a protective oxide layer on their surfaces. The Fe–Cr based alloys like for example the Crofer ferritic stainless steels are the important class of such alloys. These alloys are commonly employed in high-pressure, high-temperature vessels and as metal connections in solid oxide fuel cells (SOFCs). Crofer stainless steels consist of ferrite α matrix and Laves phase strengthening precipitates. The morphology of Laves phase in the α/α grain boundaries (GBs) in Crofer 22 H alloy is studied in this work. The morphology of GB precipitates of the second solid phase depends on the ratio between the energy σαα of α/α GBs in the matrix phase and the energy of α/β interphase boundaries σαβ. If σαα > 2σαβ, the second phase β forms continuous layers between the matrix α grains. In this case, one speaks about complete GB wetting by the second solid phase. If 2σαβ > σαα, the second phase forms chains of lenticular particles in the grain boundary, and the incomplete (or partial) GB wetting is observed. In this work, we annealed the Crofer 22 H samples at different temperatures between 550 and 950 °C during long time (600–3000 h) in order to reach the equilibrium state. Thus, we observed for the first time the complete and incomplete wetting of α/α grain boundaries in the ferrite matrix of the Crofer 22 H alloy by the Laves phase (with Fe2M structure, rich on Ti, W and Nb). Below 600 °C all ferrite GBs are completely wetted by the continuous layers of the Laves phase. Between 600 and 900 °C the portion of completely wetted GBs continuously decrease with increasing temperature from 100 to 0

The iron-carbon system is the basis of all binary, as well as many low- and high-alloyed steels. In this paper, the phenomenon of the so-called wetting of grain boundaries (GBs) by the second solid phase is studied for the first time in the Fe–C system. This phenomenon was observed in the regions of the Fe–C phase diagram where two different solid phases are in equilibrium. In the case of complete GB wetting by the second solid phase, its continuous layers completely separate the grains of the matrix. If the GB wetting is incomplete (or partial), then the second phase forms a chain of lenticular inclusions along the GB. With a change in temperature, a transition from complete wetting to incomplete wetting and vice versa can occur. The morphology of precipitates of the second solid phase in grain boundaries depends on the ratio of the GB energy σGB and the energy of interphase boundaries 2σαβ between two solid phases α and β. If σGB > 2σαβ, the second phase forms continuous layers between the matrix grains. In this case, one speaks about GB complete wetting by the second solid phase. If 2σαβ > σGB, the second phase forms chains of lenticular particles in the grain boundary, and the incomplete wetting is observed. Consider first the two-phase area of the Fe–C phase diagram where austenite (carbon solid solution in the fcc γFe) and cementite Fe3C are in equilibrium. Above 905 °C all γFe/γFe GBs are completely wetted by Fe3C layers. Below 850 °C all γFe/γFe GBs are partially wetted by Fe3C. In the αFe + γFe area, all γFe/γFe GBs are completely wetted by the αFe layers above 782 °C. Below 750 °C all γFe/γFe GBs are partially wetted by αFe. In the αFe + Fe3C area of the Fe–C phase diagram no complete GB wetting was observed.

The effect of rotary swaging (RS) on the microstructure, mechanical properties, corrosion resistance and biocompatibility in vitro and in vivo of the Zn-1Mg-0.1Mn (wt%) alloy was studied in this work. A structure with alpha-Zn grains elongated along the deformation direction and spherical particles of the eutectic phase are formed in the Zn-1Mg-0.1Mn alloy after RS. RS also leads to the formation of an ultrafine-grained structure with a grain size of less than 1 mu m and the precipitation of MnZn13 particles. The formation of such a microstructure increases the strength (YS up to 274 +/- 8 MPa, UTS up to 295 +/- 4 MPa) and fatigue limit (sigma R = 130 MPa) of the alloy without loss of ductility. At the same time, RS does not lead to deterioration of the corrosion resistance of the alloy and cause a tendency to slow down the degradation process. The biocompatibility in vitro of the Zn-1Mg-0.1Mn alloy both before and after RS is at an acceptable for medical use level. It is also interesting that the alloy does not promote the growth of adenocarcinoma cells line SKBR3. Implantation of the alloy under the periosteum of the mice tibia does not cause the formation of foci of osteomalacia or accumulation of pus, as well as processes of rejection of samples or tissue inflammation. In this regard, it can be concluded that the alloy can be considered a promising material for use in orthopedic oncology.

The effect of preliminary annealing at 1000°C and subsequent high-pressure torsion (HPT) on the phase composition and mechanical properties of titanium alloys with 2, 4, 6, and 8 wt

The multicomponent equiatomic CrMnFeCoNi alloy was proposed by B. Cantor almost 20 years ago and was the first in the family of the so-called multiprincipal or high-entropy alloys (HEAs). Various mechanical properties of the Cantor alloy and its derivatives, such as corrosion behavior, oxidation resistance, irradiation response, diffusion bonding, and weldability, have been studied these past years. Unfortunately, data on their thermo-physical properties are scarce and the information about infrared emissivity is completely absent. Having reliable infrared emissivity data at working conditions is very important for non-contact temperature measurements and for modeling heat transfer by radiation during manufacturing. In this work, a Cantor alloy, as a typical example of HEAs, was manufactured with levitation melting in vacuum. The alloy contains mainly one phase with face-centered cubic lattice and small amount of oxide precipitates. The angle-dependent spectral directional emissivity was measured between 200 and 700 °C. Reproducible data were obtained upon several thermal cycles. The total directional emissivity is almost constant from 10° to 50°, and it increases up until it reaches a maximum around 70°. Integrating these data, total hemispherical emissivity was determined, and it was observed that this property remains almost constant at 0.28 in a wide temperature range, showing a minor increase with increasing temperature. Spectral directional emissivity measurements allow detecting incipient oxidation processes. These data show the necessity of measuring emissivity at working temperatures to achieve a precise quantification of radiative heat transfer.

The structure, aging kinetics, and mechanical properties of new Mg–Sm–Tb–Zr alloys, which are prepared by hot extrusion and differ in the content of rare-earth metals and their ratio, are studied. Samarium and terbium are found to differently affect recrystallization during deformation and the character of strengthening, which occurs in the course of additional aging for different times and results from the decomposition of a magnesium-based solid solution. The mechanical properties of the alloys subjected to hot extrusion and aging, in particular, upon heating in the temperature range up to 300°C, are determined.

The specimens of Ti-2 wt % Fe alloy were annealed at three different temperatures, in the β-Ti, (α-Ti + β-Ti) and (α-Ti + TiFe) fields of the Ti-Fe phase diagram, then water quenched and subjected to high-pressure torsion (HPT). The X-ray diffraction analysis showed that the main phase in all annealed samples was the α phase (more than 90%), while the main phase after HPT was the ω phase. The hardness H and Young’s modulus E were determined by nanoindentation at the center, in the middle of the radius, and near the edge of each specimen. It was found that the H and E values were different for specimens annealed at different temperatures and depended on the radial coordinate of the indentation region. The maximum H values were obtained in the middle of the radius of the specimens. The E values of all specimens decreased from the center to the edge, reaching very low values. The paper discusses structure transformations during HPT, the behavior of the radial dependences of H and E , and probable causes of a strong decrease in E values.

Periodic electric current pulses, i.e. electropulses, were applied on selective laser melting prepared 15-5 precipitation hardening stainless steel for direct aging. Traditional aging treatment typically takes hours to achieve peak hardening and could induce reverted austenite. Herein, electropulsing treatment on as-built sample can dramatically reduce the processing time to 6 min. Moreover, the nucleation of reverted austenite triggered by the segregation of Ni atoms on the interfaces between Cu-rich precipitates and martensite was not observed. These two unique phenomena were rationalized to the unsynchronized enhancement of diffusivity of Cu and Ni atoms under electropulses due to their different electron configurations.

Although vanadium is used in many alloys as an alloying element, the binary Ti–V system has been studied very poorly. In particular, the effect of heat treatment in combination with high-pressure torsion (HPT) has not been studied at all for this system. The Ti-2 wt

The mutual influence of the primary and secondary order parameters when high pressure torsion is applied is studied. Equilibrium and nonequilibrium cases are considered. The first is realized with a continuous increase in torque, and the second, when studying the transition from one state to another, described by a traveling wave. The consideration is carried out on the basis of Landau’s thermodynamic theory.

The simple oxides like titania, zirconia, and ZnO are famous with their antibacterial (or even antimicrobial) properties as well as their biocompatibility. They are broadly used for air and water filtering, in food packaging, in medicine (for implants, prostheses, and scaffolds), etc. However, these application fields can be broadened by switching to the composite multicomponent compounds (for example, titanates) containing in their unit cell, together with oxygen, several different metallic ions. This review begins with a description of the synthesis methods, starting from wet chemical conversion through the manufacturing of oxide (nano)powders toward mechanosynthesis methods. The morphology of these multicomponent oxides can also be very different (like thin films, complicated multilayers, or porous scaffolds). Further, we discuss in vitro tests. The antimicrobial properties are investigated with Gram-positive or Gram-negative bacteria (like Escherichia coli or Staphylococcus aureus) or fungi. The cytotoxicity can be studied, for example, using mouse mesenchymal stem cells, MSCs (C3H10T1/2), or human osteoblast-like cells (MG63). Other human osteoblast-like cells (SaOS-2) can be used to characterize the cell adhesion, proliferation, and differentiation in vitro. The in vitro tests with individual microbial or cell cultures are rather far away from the real conditions in the human or animal body. Therefore, they have to be followed by in vivo tests, which permit the estimation of the real applicability of novel materials. Further, we discuss the physical, chemical, and biological mechanisms determining the antimicrobial properties and biocompatibility. The possible directions of future developments and novel application areas are described in the concluding section of the review.

The specimens of Ti-2 wt % Fe alloy were annealed at three different temperatures, in the beta-Ti, alpha-Ti + beta-Ti and alpha-Ti + TiFe fields of the Ti-Fe phase diagram, then water quenched and subjected to high-pressure torsion (HPT). The X-ray diffraction analysis showed that the main phase in all annealed specimens was the alpha phase (more than 90%), while the main phase after HPT was the omega phase. Hardness H and Young's modulus E were determined by nanoindentation at the center, in the middle of the radius, and near the edge of each specimen. It was found that the H and E values were different for specimens annealed at different temperatures and depended on the radial coordinate of the indentation region. The maximum H values were obtained in the middle of the radius of the specimens. The E values of all specimens decreased from the center to the edge, reaching very low values. The paper discusses structure transformations during HPT, the behavior of the radial dependences of H and E, and probable causes of a strong decrease in E values.

The effect of cold rotary swaging (RS) and subsequent aging on the structure, electrical conductivity, mechanical characteristics and fracture toughness of the Cu-0.77%Cr-0.86%Hf alloy was studied. RS leads to the formation of a microstructure elongated along the direction of deformation with grains width of 8.0 ± 0.2 μm. An ultrafine-grained structure with shear bands of 370 ± 10 nm in width and subgrains of 500 ± 13 nm in size is formed inside these elongated grains. The refinement of the microstructure after RS leads to an increase in ultimate tensile strength (UTS) from 300 ± 5 to 505 ± 12 MPa and a decrease in ductility from 54.0 ± 2.4 to 12.9 ± 0.3%. A subsequent aging of the alloy leads to the precipitation of fine particles of Cr and Cu 5 Hf phases. The precipitation of these particles leads to an additional increase in UTS of RS-treated alloy up to 558 ± 11 MPa and ductility up to 15.4 ± 2.4%. In this case, the decomposition of the supersaturated solid solution, which accompanies the particles precipitation, leads to an increase in the electrical conductivity of the deformed alloy up to 77.7 ± 1.6%IACS. The combination of RS and subsequent aging at a temperature of 450 °C for 4 h leads to an increase in the fatigue limit from 220 to 393 MPa. In addition, this treatment allows to increase the fracture toughness coefficient by 6 times.

During the high pressure torsion (HPT) of a material, a steady-state is reached after a certain number of the plunger revolutions. This steady-state is determined by the dynamic equilibrium between the formation of crystal lattice defects during deformation and their relaxation. In particular, during HPT of binary solid solutions, the competition takes place between the dissolution of particles of the second phase (and enrichment of the solid solution), on the one hand, and the decomposition of the solid solution (and precipitation of the second phase), on the other hand. As a result, a certain steady-state concentration of the second component css appears in a binary solid solution during HPT. This concentration is equifinal, it depends only on the HPT conditions, but not on the initial state of the binary alloy. In copper-silver alloys subjected to HPT at room temperature, this concentration is css = 5.5 wt.

On the basis of phenomenological theory in the Landau approximation, a model is developed to describe experiments on measuring the nanohardness of binary titanium-based solutions when high pressure torsion is applied. The possible mechanisms for the appearance in the experiment of asymmetry of this magnitude relative to the middle of the radius of a cylindrical sample are determined. Additionally, the behavior of the radial and angular components of nanohardness in the presence of a point defect in the material is studied.

Three titanium alloys with 0.5, 6, and 9 wt.% iron were investigated, and the samples were pre-annealed in three different regions of the Ti–Fe phase diagram, namely β, α+β, and α+FeTi. After annealing, five samples of different phases and structural compositions were studied. They were then subjected to the high-pressure torsion (HPT). The microstructure of the samples before and after HPT treatment was studied using transmission and scanning electron microscopy. The microstructure of the samples obtained during heat treatment before HPT treatment had a fundamental effect on the microstructure after HPT. Grain boundary layers and chains of particles formed during the annealing process made it difficult to mix the material during HPT, which led to the formation of areas with non-uniform mixing of components. Thus, the grain boundary layers of the α-phase formed in the Ti–6wt % Fe alloy after annealing at 670 °C significantly decreased the mixing of the components during HPT. Despite the fact that the microstructure and phase composition of Ti–6wt % Fe alloys pre-annealed in three different regions of the Ti–Fe phase diagram had significant differences, after HPT treatment, the phase compositions of the studied samples were quite similar. Moreover, the measured micro- and nanohardness as well as the Young’s modulus of Ti–6wt % Fe alloy had similar values. It was shown that the microhardness of the studied samples increased with the iron content. The values of nanohardness and Young’s modulus correlated well with the fractions of β- and ω-phases in the studied alloys.

When a multicomponent NdFeB-based magnetic alloy is deformed using high-pressure torsion (HPT), a quasistationary state is reached after 2.5 anvil revolutions, which corresponds to an equivalent strain of similar to 40 at the sample mid-radius. In this state, torque self-oscillations are observed with a period of about 1.5 s and an amplitude of similar to 10 % around the average value of 550 N m(-1). Such selfoscillations are accompanied by strong acoustic emission. Before HPT, the alloy under study has an almost rectangular hysteresis loop with saturation magnetization Js = 135 emu g(-1) and coercivity H-c = 34.8 kOe. HPT deformation at initial stages transforms this alloy to the class of soft magnets: H-c drops to 1.35 x 10(-4) kOe, while J(s) practically does not change. An increase in strain leads to a gradual increase in H-c to 9.61 kOe and a decrease in J(s )to similar to 100 emu g(-1) at the number of anvil revolutions n = 7. This is explained by HPT modification of the regular grain-boundary network of neodymium-rich paramagnetic phase layers. These layers provide magnetic isolation between grains of the Nd2Fe14B ferromagnetic phase. Periodic changes in torque and J(s) with increasing torsion angle are caused by transitions from the amorphous phase to the crystalline one and vice versa.

Comparative studies are conducted on the structure and mechanical properties of the ultrafine-grained Ti-5Al-5V-5Mo-1Cr-1Fe alloy obtained by abc pressing and radial shear rolling with subsequent aging. It is shown that the ultrafine-grained structure formed by these methods provides increased strength properties under both tension and three-point bending compared to the initial coarse-grained state. At the same time, the alloy obtained by abc pressing demonstrates a higher fracture resistance during three-point bending compared to the alloy obtained by radial shear rolling + aging due to its enhanced ductility. This also determines the ductile fracture pattern of the ultrafine-grained alloy obtained by abc pressing during three-point bending in contrast to ductile-brittle fracture of the alloy obtained by radial shear rolling + aging.

The effect of cold rotary swaging (RS) and subsequent aging on the structure, electrical conductivity, mechanical characteristics and fracture toughness of the Cu-0.77