The attractive physical, mechanical, and operational characteristics of the structural metal materials most widely used in the world economy can be achieved through diffusion-free phase martensitic transformations (MT) in combination with their atomic ordering and decomposition of the supersaturated solid solutions [...]

A comprehensive study of the influence of hot rolling on structural-phase transformations and physical and mechanical properties of a metastable (alpha + beta) alloy with a shape memory effect Cu-41 wt % Zn is carried out. Structural-phase transformations are investigated using optical and electron microscopy, X-ray phase analysis, and differential scanning calorimetry (when heated). It is discovered that intermediate bainitic transformations occur in the alloy along with the formation of martensitic phases. The peculiarities of the mechanical behavior of the alloy are established when testing samples using the uniaxial tensile method after hot rolling and subsequent heat treatments. It is established that hot rolling with a total reduction of 90% and subsequent heat treatment lead to an increase in the ductility of the alloy up to 48%.

A comprehensive study of the influence of hot rolling on structural-phase transformations and physical and mechanical properties of a metastable (α + β) alloy with a shape memory effect Cu–41 wt

A comprehensive study of structural-phase transformations and physical and mechanical properties of metastable Cu-39.5 wt % Zn alpha + beta alloy with the shape memory effect subjected to thermomechanical treatments including cold rolling and annealing has been carried out. The features of the fine structure formed at the intermediate and bainitic phase transformations have been studied using optical and electron microscopy as well as X-ray phase analysis. The temperature intervals of bainitic 3R/9R and other phase transformations were established by differential scanning calorimetry upon heating up to 500 degrees C. In the case of the hardened alloy, the temperature of the bainitic transformation was close to 170 degrees C. In mechanical tests conducted using uniaxial tension, it has been demonstrated that cold deformation and post-deformation heat treatment under different modes can be employed to obtain the alloy in high-strength or ductile states. These states are characterized by an ultimate strength (sigma u) greater than 700 MPa and a relative elongation (delta) greater than 40%, respectively.

The martensitic transformations in Cu–38Zn and Cu–39.5Zn (wt β _2^' (3R) and γ _2^' (2H) have been identified in Cu–38Zn alloys, as well as β _2^” (9R) and γ _2^' (2H), in Cu–39.5Zn alloys. The proposed crystallographic models of martensitic rearrangement in the alloys are based on an analysis of X-ray and electron diffraction, including diffuse electron scattering, as well as on the packing defects of the internal substructure of martensite.

The microtexture and microstructure of the industrial Ti–6Al–4V alloy almost in the single-phase α state, obtained using the thermomechanical treatment including the hot rolling, are studied by the X-ray diffraction analysis method and optical and transmission and scanning electron microscopy. It is established that the layered fine-grained microstructure in the cross section of the plate perpendicular to the rolling direction is characterized by selection of equiaxed globular α grains that obey Burgers orientation relationships and twinning orientations. The revealed distributions of α grains over dimensions and crystallographic orientations in the plate’s cross section are related to the peculiarities of distributions established for the plane of plate rolling. The structural mechanisms of generating the microtexture regions in the alloy are discussed.

Features of the microstructure of the shape-memory Ti–51 at

Methods of transmission and scanning electron microscopy are used to study premartenstic states and their relation to martensitic transformations in the alloys Cu–38 wt β _2^' , β2 → β _2^” , and β2 → γ _2^' are proposed based on the crystallographic data obtained in the premartensitic state.

The commercial Ti–6Al–4V alloy was obtained in an almost single-phase state, formed by finely dispersed globular α-grains with an average size of 12 μm, using thermomechanical processing, including hot rolling. The microtexture and structure of the alloy were studied using X-ray diffractometry and transmission and scanning electron microscopy, including orientation microscopy. It is found that for α-grains the Burgers orientation relationships are satisfied, and twin orientations are ensured in the rolling plane. A significant scattering of the crystallographic orientations of α-grains relative to each other (up to 10°–15°) is established for each group of close Burgers orientations as a result of plastic deformation by rolling at high temperatures. Clusters of microtexture regions in the layered microstructure of grains and the formation mechanisms and mutual crystallographic misorientations of microtexture regions and grains in the alloy have been identified.

A comprehensive study of structural-phase transformations and physical and mechanical properties of metastable Cu–39.5 wt

For the first time, data on the peculiarities of the structure of the Cu–Al–Ni–(B) alloys differing in the contents of alloying elements, namely, containing 10–14 wt % aluminum, 3, 4, 4.5 wt % nickel, and 0.02–0.3 wt % boron were obtained using optical, scanning, and transmission microscopy and X-ray diffraction analysis along with measurements of tensile mechanical properties. The effect of boron on the grain size, structure, phase composition, and mechanical properties of the shape-memory alloys has been studied. The localization of aluminum boride precipitates in the structure has been studied, and the effect of grain growth retardation in (α + β) and β Cu–Al–Ni–B alloys in both cast and heat-treated states has been found.

For the first time, using optical, scanning, and transmission electron microscopy and X-ray phase analysis in combination with measurements of tensile mechanical properties, we obtained data on the structural features of the polycrystalline shape-memory eutectoid Cu-Al-Ni-(B) alloys doped by aluminum (of 10 and 14 wt% Al in total amount), nickel (of 3, 4, and 4.5 wt% Ni), and boron (0.02–0.3 wt% B) in various compositions. The effect of boron on the grain sizes, structure, phase composition, and mechanical properties of shape memory (SM) alloys has been studied. The localization of aluminum borides in the structure was investigated and an effect of grain growth inhibition in the (α + β) and β Cu-Al-Ni-B alloys was established, both in the cast state of the alloys considered and after their heat treatment.

The paper presents studies of the mechano-structural characteristics of the atomically ordered Cu3Pd alloy subjected to severe plastic deformations (SPDs) at room and cryogenic temperatures combined with subsequent annealings. Transmission and scanning electron microscopy (TEM and SEM), X-Ray diffraction (XRD) analysis and microhardness tests were used as research methods. The mechanical characteristics of the synthesized Cu 3 Pd alloy were compared after preliminary SPDs at room and cryogenic temperatures as well as during subsequent annealings. The significant acceleration of the atomic ordering kinetics and, consequently, effective diffusion during recrystallization annealing after cryodeformation was found. The developed deformation-thermal method can be used to synthesize high-strength nanostructured resistive and electrocontact materials.

The paper presents the results of a comparative analysis of the structure of Ti 2 NiCu alloy subjected to severe plastic deformation by high pressure torsion and subsequent annealing. The structure of the alloy was studied using diffractometry, electron microscopy, X-ray and neutron techniques, as well as transmission electron microscopy. The analysis has revealed the formation of an amorphous-crystalline state within the alloy, with B 2-lattice nanocrystallites present in the amorphous matrix. The analysis of diffuse maxima has indicated that the Ti 2 NiCu alloy, after subjecting to high pressure torsions till five turns, possesses topological and compositional short-range order in the form of nanodomains with a superstructure arranged by B 2 and L 2 1 order.

Mechano-structural characteristics of the synthesized Cu 72 Au 24 Ag 4 and commercial Cu 59 Au 33 Ag 7 Fe 1 alloys subjected to preliminary severe plastic deformations (SPDs) by high-pressure torsion combined with subsequent annealings at different temperatures and holding times were studied by means of scanning and transmission electron microscopy as well as durometry. Due to SPDs, it was possible to refine the structure of the investigated alloys to submicro- and nanostructural state. As a result of certain annealing regimes, the atomic ordering processes began to occur in the alloys. The microstructural features and mechanical properties after preliminary SPDs and subsequent annealings were compared for the studied alloys. Influence of the deformation degree and subsequent annealing regimes on the kinetics of atomic ordering and changes in mechanical properties was shown. In addition, it was found the inhibition effect of the nanograin growth due to the barrier action of dispersed precipitates.

Polycrystalline boron-alloyed α + β Cu–Al–Ni compositions subjected to high-temperature thermomechanical treatment (HTMT) via forging and rolling are studied for the first time. Optical, scanning, and transmission electron microscopy and X-ray diffraction analysis were used in combination with measurements of tensile mechanical properties to study the peculiarities of the microstructure, phase composition, and mechanical properties of these alloys. The peculiarities of the microstructure and mechanical behavior of alloys differing in their aluminum and boron contents, which were subjected to HTMT, have been determined. The alloys were prepared in the fine-grained state, which determines the increase in the functional strength and plastic characteristics. A schedule of HTMT of bulk Cu–Al–Ni–(B) alloys is proposed.

The effect of thermomechanical treatment on the structure and phase transformations of the Ti–50.5 at

We present a brief overview of the structural and phase transformations and mechanical properties of bulk binary TiNi shape memory alloys, which demonstrate attractive commercial potential. The main goal of this work was to create a favorable microstructure of bulk alloys using both traditional and new alternative methods of thermal and thermomechanical processing. It was found that the implementation of an ultrafine-grained structure by different methods determined an unusual combination of strength, ductility, reversible deformation, reactive resistance of these alloys to subsequent tensile or torsion tests at room temperature, and, as a consequence, the highly reversible effects of the shape memory and superelasticity. It is shown that the alloys Ti49.8Ni50.2 and Ti49.4Ni50.6 are incapable of aging, and, after being subjected to ECAP, were characterized by their high strength (σu up to 1200 MPa) and ductility (δ up to 60–70%). A combined treatment of multi-pass rolling and HT of the Ti49.5Ni50.5 and Ti49Ni51 alloys prone to aging have provided even greater strength (σu up to 1400–1500 MPa) with slightly lower ductility (25–30%). The microstructure, phase composition, and martensitic transformations in Ti-Ni alloys with varying Ni concentrations ranging from 50 to 51 wt.% were investigated by TEM, SEM, and X-ray methods. The mechanical behavior of the alloys was studied during tensile and torsion tests.

An overview of modern material science problems is presented for ultralightweight high-modulus commercial Al-Li-based alloys in historical retrospect. Numerous particular examples of the Soviet and Russian aviation whose various designs were made of these alloys confirm their successful innovative potential. The key regularities of multicomponent alloying are discussed for the master alloys and modern commercial Al-Li-based alloys of the latest generation; the features typical of their microstructures, phase composition, and properties formed during aging are analyzed. The main mechanisms of phase formation are generalized for standard thermal and thermomechanical treatments. Recent original achievements have been obtained in designing of unique structural and phase transformations in these commercial alloys by means of methods of severe plastic deformations followed by heat treatment and storage. Using the example of three Russian commercial alloys of last generation, the basic principles of creating and controlling an ultrafine-grained structure, the origin and growth of stable nanophases of various types and chemical composition that determine the physicomechanical properties of alloys are established.