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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. [ABSTRACT FROM AUTHOR]

The effect of equal-channel angular pressing (ECAP) at 150°C and subsequent aging on the structure and strength characteristics of Al–Mg2Si alloys with scandium and joint (Sc + Zr) and (Sc + Hf) additions is studied. Hardness and electrical resistivity curves demonstrate the decomposition of the supersaturated solid solution in the alloys with (Sc + Zr) and (Sc + Hf) additions is found to be same, and the optimum aging conditions of the alloys are obtained. The microstructure of the alloys and precipitation of secondary phases are studied in detail using scanning and transmission electron microscopy (SEM and TEM, respectively). The alloys subjected to ECAP and aging demonstrate an increase in the strength and the plasticity due to compensation of aging processes by recovery processes related to restructuring a dislocation structure. [ABSTRACT FROM AUTHOR]

The kinetics of microcracks accumulation and fracture at various stages of tension of grade 20 steel samples with coarse-grained and ultrafine-grained (UFG) structure obtained by equal-channel angular pressing (ECAP) has been studied. To research the effect of mechanical degradation, a part of the samples were subjected to preliminary cycling to a relative lifetime of 50%, followed by tensile tests, during which the parameters of acoustic emission and deformation fields obtained by digital image correlation were evaluated, and the intensity of the residual magnetic field was measured. The length and density of surface microcracks were measured by optical microscopy using computer image analysis. It is established that pre-cycling causes hardening of the material and a decrease in its plasticity. The fracture stages were revealed, and the origins of fatigue cracks were found on the internal delaminations of samples with a UFG structure after preliminary cyclic loading. It is shown that the formation of the UFG structure after the ECAP of samples made of grade 20 steel leads to hardening and reduction of the fracture work, the area of the plastic zone, maximum major deformations and damage, as well as to an increase in the number of AE signals and the intensity of the residual magnetic field. [ABSTRACT FROM AUTHOR]

Abstract—The effect of rotary swaging (RS) at a strain ε = 1.28 and 2.31 on the microstructure, corrosion resistance, and mechanical properties of a potential medical Mg–1.1% Zn–1.7% Dy alloy is studied. RS at ε = 1.28 is shown to lead to almost 10-fold grain refining (from 300–400 to 30–40 μm). An increase in the strain to ε = 2.31 leads to the formation of a nonuniform microstructure characterized by areas containing grains both 30–40 and 5–10 μm in size. The grain refining after RS results in an increase in the electrochemical corrosion resistance (corrosion potential increases from –1550 ± 9 mV, which is observed for the quenched state, to –1442 ± 23 and –1454 ± 35 mV, which correspond to the alloy subjected to RS at ε = 1.28 and 2.31, respectively) but does not cause changes in the corrosion current density. In this case, the degradation rate of the alloy increases up to 3.46 ± 1.06 mm/year as the strain increases. The structure refining observed after RS at ε = 1.28 results in a substantial increase in the strength of the alloy as compared to that of the quenched alloy (ultimate strength increases from 70 ± 13 to 273 ± 7 MPa) and a decrease in the plasticity from 23.1 ± 5.1 to 14.0 ± 2.9%. An increase in the strain to ε = 2.31 does not increase the strength of the alloy (σu = 267 ± 4 MPa) and causes an increase in the plasticity (δ = 21.1 ± 1.6%), which is likely to result from textural changes having occurred in the alloy. [ABSTRACT FROM AUTHOR]

Abstract—The structure, electrical conductivity, and mechanical properties (including fatigue strength) of a Cu–0.8% Hf alloy after rotary swaging (RS) at various strains and subsequent aging are investigated. RS is shown to cause the formation of a microstructure elongated in the deformation direction. When the strain increases, the average grain width decreases and grains acquire an increasingly elongated shape. After RS at ε = 2.77, the formation of an ultrafine-grained structure with an average subgrain size of 173 ± 12 nm is observed inside the elongated grains. When the strain increases, the strength of the alloy increases and the plasticity decreases. Subsequent aging causes an increase in the strength of the quenched alloy and the alloy after RS at ε = 0.58 and 1.39; hardening is absent after RS at ε = 2.77. In all cases, aging increases the electrical conductivity of the alloy as a result of the decomposition of a supersaturated solid solution and the precipitation of the Cu5Hf phase. The best combination of the mechanical and functional properties is achieved after RS at ε = 2.77 and subsequent aging at 475°C for 2 h: the ultimate tensile strength is 461 ± 28 MPa, the ductility is 12.5 ± 2.4%, the fatigue limit is 325 MPa, and the electrical conductivity is 90.4 ± 1.9% IACS. [ABSTRACT FROM AUTHOR]

Abstract—The effect of the microstructure of Zn–1% Mg and Zn–1% Mg–0.1% Ca alloys after treatment under various conditions (casting, annealing, aging) on their mechanical and corrosion properties has been studied. The addition of calcium is shown not to degrade the strength and corrosion properties of the Zn–1% Mg alloy. The change in the microstructure of the alloys during annealing and aging significantly affect their corrosion resistance and mechanical characteristics. For example, annealing of both alloys leads to an increase in their corrosion resistance and a decrease in the ultimate tensile strength and plasticity at a simultaneous increase in the yield strength. Subsequent aging at 150°C for 1 h slightly decreases the corrosion characteristics and causes further softening of the alloys at a slight increase in their plasticity. Our results demonstrate that, for the alloys under study to be successfully used as medical materials, they should be subjected to deformation treatment in order to increase their strength and plasticity as a result of microstructural and textural transformations. [ABSTRACT FROM AUTHOR]

The possibility of producing alloys, which are characterized by high degradation rate and used for manufacturing biodegradable implants, is studied on Fe–Mn–C alloys subjected to equal-channel angular pressing (ECAP). In particular, the attention is paid to the preparation of alloys, which have an ultrafine-grained structure and a high density of boundaries of structural elements and are in completely austenitic state. The effect of a structure on the corrosion rate, the mechanical properties, and in vitro biocompatibility has been revealed. An analysis of X-ray diffraction and transmission electron microscopy data for the alloys subjected to ECAP shows the formation of an austenitic partially or completely twin structure. The formed structure determines a high level of the strength characteristics while maintaining an adequate plasticity. As the uniformity of the twin structure and density of twin packets increases and the twin size decreases, the corrosion rate is shown to decrease. Based on results of in vitro studies of the hemolytic efficiency and cytotoxicity, the biocompatibility of the alloys subjected to ECAP is retained. The treatment conditions of samples are found not to affect their biocompatibility and to ensure a similar level of the adherence of mesenchymal cells with an osteogenic potential on the surface of the alloy samples subjected to ECAP. [ABSTRACT FROM AUTHOR]

The effect of rotary swaging (RS) at various strains and subsequent aging at various temperatures on the structure and the mechanical properties of a Cu–0.5% Cr–0.08% Zr alloy is studied. RS is shown to form a microstructure with grains extended along the deformation axis. The grain size decreases with increasing strain. Subgrains 300–400 nm in size and shear bands 200 nm in width are observed inside the elongated grains formed upon RS at ε = 2.77. Microstructural refinement significantly increases the strength of the alloy but decreases its plasticity. Subsequent aging further increases the strength and the electrical conductivity of the alloy due to the precipitation of fine chromium and Cu5Zr-phase particles. Quenching, RS at ε = 2.77, and subsequent aging at 500°C for 1 h result in the best combination of strength (557 ± 18 MPa), plasticity (17.1 ± 2.6%), and electrical conductivity (83.4 ± 1.6% IACS) of the Cu–0.5%Cr–0.08%Zr alloy. [ABSTRACT FROM AUTHOR]

The effect of equal-channel angular pressing (ECAP) and subsequent aging on the structure and mechanical properties of Cu–7% Cr and Cu–10% Fe alloys is studied. ECAP is shown to substantially refine the structure of both alloys. The average grain and subgrain sizes of the Cu–7% Cr and Cu–10% Fe alloys subjected to ECAP are 250 ± 13 and 155 ± 7 nm, respectively. Moreover, the presence of shear bands ~100 nm wide is found for the alloys. The structure refinement results in a substantial increase in the strength of the alloys and a simultaneous decrease in their plasticity. In this case, additional aging of the alloys, which is performed after quenching, increases their microhardness, electrical conductivity, and strength; simultaneously, the plasticity decreases. Aging of the alloys subjected to ECAP leads to an increase in the sizes of the structural components (both shear bands and grains and subgrains) and to the precipitation of chromium and iron phases from the Cu–7% Cr and Cu–10% Fe alloys, respectively. The average sizes of shear bands, grains, and subgrains of the Cu–7% Cr and Cu–10% Fe alloys subjected to ECAP and aging are 130 ± 7 and 317 ± 24 nm and 220 ± 9 and 357 ± 27 nm, respectively. Aging does not affect the strength of the deformed Cu–7% Cr alloy and leads to a softening of the deformed Cu–10% Fe alloy. Aging of both alloys subjected to ECAP leads to an increase in their plasticity and electrical conductivity. In the case of the Cu–7% Cr alloy, treatment, which consists in quenching, ECAP, and aging, ensures reaching a better combination of the strength (~470 MPa), plasticity (~18%), and electrical conductivity (~81% IACS). [ABSTRACT FROM AUTHOR]

Optical microscopy and hardness measurements are used to study the influence of (Sc + Zr) and (Sc + Hf) transition metal additions and severe plastic deformation by equal-channel angular pressing (ECAP) on the temperature of recrystallization in aluminum Al–Mg2Si alloys. Recovery is revealed to take place in the Al–Mg2Si alloys in the temperature range 200–600°C. Joint scandium and hafnium alloying of the ECAP-deformed alloys weakens softening during recrystallization due to the formation of a structure with grains smaller than those in the structure formed in the alloys free from transition metals. [ABSTRACT FROM AUTHOR]

We studied morphofunctional properties of human blood cells and diploid culture cells exposed to different types of magnesium materials: pure magnesium (Mg), magnesium—yttrium—neodymium—zirconium alloy (Mg-Y-Nd-Zr) and magnesium—zinc—calcium alloy (Mg-Zn-Ca). The materials were incubated with donor blood and mesenchymal multipotent stromal cells over 3 days. The studied materials did not induce massive lysis of human erythrocytes and leukocytes in vitro, but gradually impaired their structural integrity. In all cases, spontaneous platelet aggregation was observed in 6 h. In the presence of pure Mg and Mg-Zn-Ca alloy, this was accompanied by a decrease in the number of platelets with granules. In 24 h, substantial platelet degranulation occurred in all cases and in 72 h, the platelets did not contain granules. In parallel, the formation of large aggregates (60 μ) was observed. In the culture of stromal cells, all Mg-based materials reduced structural integrity of cells in 24 h, but did not significantly inhibit cell proliferation. Structural integrity of stromal cells partially recovered by day 3 in culture. The studied materials (Mg, Mg-Y-Nd-Zr, and Mg-Zn-Ca) seemed to be low-toxic for human cells during short-term contact, but could stimulate platelet aggregation and spontaneous degranulation and reduced the viability of diploid cells in vitro. [ABSTRACT FROM AUTHOR]

Abstract: The structure homogeneity of the Mg-0.8% Ca alloy is shown to increase with temperature during uniaxial compression. Plastic deformation localizes in narrow and wide deformation bands at 250-350°C. A small number of regions with recrystallized grains is observed only after deformation at 400°C. A relatively homogeneous recrystallized structure with an average grain size of about 20 μm forms after uniaxial compression at t = 450°C. Multiaxial deformation at decreasing temperature in the range 450-250°C significantly refines the initial structure of the Mg-0.8% Ca alloy to an average grain size of 2.1 μm. This structure leads to a significant hardening, namely, an increase in the yield strength to 193 MPa and the tensile strength to 308 MPa. The relative elongation after multiaxial deformation increases by more than two times. [ABSTRACT FROM AUTHOR]

Atomic force microscopy is used to study the nanostructured state of a number of Nd2Fe14B alloys. The starting alloys are synthesized in an argon atmosphere using an induction furnace. The nanostructured state of the Nd2Fe14B alloys is reached by two techniques, namely, severe plastic deformation and melt quenching; combined treatment, which includes severe plastic deformation of melt-quenched ribbons and subsequent annealing, is also used. The surface morphology of all studied samples is studied. These are used to interpret the magnetic hysteretic properties of the samples prepared by the different techniques. [ABSTRACT FROM AUTHOR]

The structure, the mechanical properties, and the electrical conductivity of the Cu-0.7% Cr-0.9% Hf alloy subjected to equal-channel angular pressing (ECAP) followed by aging are studied. The treatment that consists of ECAP and aging at 450°C for 2.5 h is shown to result in a high strength (σu = 605 MPa) and a high electrical conductivity (78% IACS) of the alloy. This combination of properties increases the resistance of the contact welding electrodes made of an ultrafine-grained Cu-0.7% Cr-0.9% Hf alloy as compared to its initial coarse-grained state. [ABSTRACT FROM AUTHOR]

The structure and properties of magnesium alloy WE43 are studied after homogenizing and rotary swaging deformation conducted in several stages with step lowering of the temperature from 400 to 325°C and increasing the extrusion ratio to 2.56 - 2.78. The deformation yields an ultrafine-grained (UFG) structure with a mean size of the structural components about 500 - 800 nm and particles of aMg41Nd5 phase with a mean size of about 300 - 400 nm. The formation of the UFG structure raises the strength of the alloy. The best combination of mechanical properties is provided by swaging with the final temperature 325°C. It is shown that the rotary swaging deformation does not affect the corrosion rate of the alloy measured by the methods of potentiodynamic polarization, loss in the mass and emission of hydrogen. [ABSTRACT FROM AUTHOR]

This article discusses application of quantitative X-ray texture analysis (QTXA) based on measurement of direct pole figures and electron backscatter diffraction (EBSD) aimed at study of peculiarities of formation of texture and structure of MA2-1pch magnesium alloy after equal channel angular extrusion (ECAE) and subsequent annealing. Shear bands with the width of 60 μm oriented at 45°–50° to the extrusion direction are revealed, where an inclined scattered basis texture is detected, and outside of these bands, a prismatic texture. As a consequence, basic sliding is activated in the shear bands, which is confirmed by the distribution of Schmid factors. The influence of texture and orientation of shear bands on anisotropy of strength mechanical properties of alloy is discussed. [ABSTRACT FROM AUTHOR]

The structure and the properties of an Mg-Y-Nd-Zr alloy (WE43) are studied after high pressure torsion (HPT) in the temperature range 20-300°C. Structure refinement proceeds mainly by deformation twinning with the formation of a partial nanocrystalline structure with a grain size of 30-100 nm inside deformation twins. The WE43 alloy is shown to be aged during heating after HPT due to the decomposition of a magnesium solid solution. HPT at room temperature and subsequent aging causes maximum hardening. It is shown that HPT significantly accelerates the decomposition of a magnesium solid solution. HPT at all temperatures considerably increases the tensile strength and the yield strength upon tensile tests and significantly decreases plasticity. Subsequent aging additionally hardens the WE43 alloy. A potentiodynamic study shows that the corrosion resistance of this alloy after HPT increases. However, subsequent aging degrades the corrosion properties of the alloy. [ABSTRACT FROM AUTHOR]

Some of the authors of this article recently demonstrated that severe plastic deformation permits the production of metallic alloys containing two coexisting amorphous phases from the crystalline multiphase NiNbY alloy. The aim herein is to provide a detailed description of the microstructure of this system of coexisting amorphous phases by transmission electron microscopy (TEM) analysis. As-cast NiNbY alloy was coarse grained and contained mainly NiY phase (grain size 25 μm) as well as NbNi, NiY, NiY, and NiY phases (grain size 3-5 μm). High-pressure torsion (4 GPa, 10 torsions) completely changed the structure. After severe plastic deformation (SPD), the sample contained two glassy phases and two other nanocrystalline NiY and NbNi phases (grain size about 20 nm). Bright-field TEM micrographs showed fine, 5-10 nm, round bubbles of bright Y-rich amorphous phase embedded in darker Nb-rich 'grains.' In turn, the dark Nb-rich grains were separated by layers of bright Y-rich amorphous phase a few nanometers thick. This stricture permits one to speak about mutual wetting of 'grain boundaries' in both amorphous phases. [ABSTRACT FROM AUTHOR]

The effect of annealing at 100–400°C on strengthening of ageing alloys of the Mg–Sm system subjected to rapid plastic deformation by torsion under pressure is studied. With the annealing temperature elevated to 200–250°C strengthening, caused by rapid plastic deformation, is retained, but it decreases with a further increase in temperature. [ABSTRACT FROM AUTHOR]

The effect of the original structure on deformation and failure in tension for submicrocrystalline aluminum alloys AMg6, Al–6.2% Mg–0.24% Sc and titanium is studied after rapid plastic deformation by equal channel angular extrusion. Combined analysis of deformation curves and acoustic emission, and also the results of metallographic and fractographic studies are provided. The effect of submicrocrystalline structure and inclusions on plastic flow resistance and failure in tension for alloys is studied. [ABSTRACT FROM AUTHOR]

It is shown that nano- ( Dg < 100 nm) and submicrocrystalline (100 nm < Dg < 1 µm) structures can be obtained in low-carbon and corrosion-resistant austenitic and ferritic steels and aluminum and magnesium alloys by severe plastic torsional deformation under hydrostatic pressure and by equal channel angular pressing. [ABSTRACT FROM AUTHOR]

The effect of various modes of thermomechanical treatment, including intense plastic deformation and postdeformation annealing, on the structure, mechanical, and functional properties of alloys based on titanium nickelide is investigated. The advantages of intense plastic deformation with annealing are shown as compared with traditional thermomechanical treatment. [ABSTRACT FROM AUTHOR]