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The last two decades have witnessed significant progress in the development of severe plastic deformation techniques to produce ultrafine-grained materials with new and superior properties. This review examines works and achievements related to the low-temperature superplasticity of ultrafine-grained aluminum alloys. The examples are provided of the possibility to observe low-temperature superplasticity in aluminum alloys at temperatures less than 0.5 Tmelt and even at room temperature, and herein, we demonstrate the cases of achieving high ductility and high strength in aluminum alloys from processing utilizing severe plastic deformation. Special emphasis is placed on recent studies of the formation of segregations of alloying elements at grain boundaries in UFG Al alloys and their influence on the development of grain boundary sliding and manifestation of low-temperature superplasticity. In addition, the current status and innovative potential of low-temperature superplasticity in aluminum alloys are observed. [ABSTRACT FROM AUTHOR]

The aim of this work is to predict, for the first time, the high temperature flow stress dependency with the grain size and the underlaid deformation mechanism using two machine learning models, random forest (RF) and artificial neural network (ANN). With that purpose, a ZK30 magnesium alloy was friction stir processed (FSP) using three different severe conditions to obtain fine grain microstructures (with average grain sizes between 2 and 3 µm) prone to extensive superplastic response. The three friction stir processed samples clearly deformed by grain boundary sliding (GBS) deformation mechanism at high temperatures. The maximum elongations to failure, well over 400% at high strain rate of 10−2 s−1, were reached at 400 °C in the material with coarsest grain size of 2.8 µm, and at 300 °C for the finest grain size of 2 µm. Nevertheless, the superplastic response decreased at 350 °C and 400 °C due to thermal instabilities and grain coarsening, which makes it difficult to assess the operative deformation mechanism at such temperatures. This work highlights that the machine learning models considered, especially the ANN model with higher accuracy in predicting flow stress values, allow determining adequately the superplastic creep behavior including other possible grain size scenarios.

Advanced structural materials are expected to display significantly improved mechanical properties and this may be achieved, at least in part, by refining the grain size to the submicrometer or the nanocrystalline range. This report provides a detailed summary of the role of grain size in the mechanical properties of metals. The effect of grain size on the high temperature behavior and the development of superplasticity is illustrated using deformation mechanism maps and the development of exceptional strength through grain refinement hardening at low temperatures is also discussed. It is shown that the deformation mechanism of grain boundary sliding, as developed theoretically, can be used to effectively predict both the high and low temperature behavior of metals having different grain sizes. This analysis explains the increase in strain rate sensitivity in ultrafine-grained metals with low and moderate melting points and the ability to increase both the strength and ductility of these materials to thereby overcome the strength-ductility paradox. The recent development of hybrid materials is also reviewed and it is demonstrated that, although these hybrids have received only limited attention to date, they provide a potential for making significant advances in the production of new structural materials.

Superplastic forming is considered a highly efficient technique for shaping intricate components from titanium matrix composites (TMCs). In this work, high-temperature TMCs with 5 vol% (TiBw + TiCp) reinforcements underwent superplastic tensile tests at various temperatures and strain rates. The results demonstrated that at all deformation temperatures (900 °C–1050 °C) and strain rates (5 × 10−3 s−1 to 10−4 s−1), the elongation of composite sheets surpassed 100%. The strain rate of 10−3 s−1 and a temperature of 1000 °C were found to yield the maximum elongation of 328.1%. At 900 °C, the matrix grains maintain a lamellar morphology during the main stage of deformation, and dynamic recovery (DRV) is the primary mechanism of matrix softening. At 1000 °C, wide-range dynamic recrystallization (DRX) takes place, and grain boundary slip coordinated by grain rotation is the main mechanism of deformation. At 1050 °C, the matrix grains undergo DRX and grow rapidly by migration, and the number of grain boundaries decreases dramatically, resulting in poor superplastic qualities. In the early stages of superplastic deformation, micropores sprout at the triple grain boundaries and at the interfaces between the reinforcements and the matrix. As the deformation proceeds, the micropores extend along the tensile direction and connect with each other to form cavity stringers (CS). The distance between the CS rapidly narrows as the stretching process continues, and eventually the CS links horizontally to form cavity coalescence (CC). Micropore dilatation around the reinforcements causes debonding and cavitation, leading to material failure.

Amorphous alloys possess increased mechanical strength. Currently, the processing and shaping of amorphous alloys employ their superplasticity in the supercooled liquid phase, which has pushed research into the evolution behavior of the supercooled liquid area during the processing of amorphous alloys. In this study, a molecular dynamics technique was applied to analyze the development rules of the supercooled liquid area and the "shear transformation zone" during laser-assisted scratching of Cu50Zr50 amorphous alloy. It was discovered through research on temperature fluctuations that laser irradiation raises the temperature of the processing region, and the formation of the supercooled liquid region moves the characteristic point of material removal to an earlier stage. As the local temperature rises, the distribution of the supercooled liquid region changes from dispersed to an angle of about 30° with regard to the scratching direction, and the angle subsequently decreases. The variable laws of the "shear transformation zone" during the scratching process were explored based on the von Mises strain theory. The findings demonstrate that when laser energy rises, the Newtonian layer warms up and the "shear transformation zone" distribution angle gradually decreases. At 20 eV/ps, the angle between the "shear transformation zone" and the scratching direction achieves its smallest value of 33°, resulting in the largest overlap with the supercooled liquid region and the lowest content of the "shear transformation zone". By constructing a mathematical model for material removal efficiency, it was established that energy in the range of 20 eV/ps to 30 eV/ps demonstrates higher removal efficiency and a steady processing process while reducing surface roughness by 6-7%. [ABSTRACT FROM AUTHOR]

A systematic analytical study of the mathematical properties of the previously constructed nonlinear model for shear flow of thixotropic viscoelastic-plastic media is continued. For arbitrary six material parameters and an (increasing) material function that control the model, the basic properties of the families of stress-strain curves at constant strain rates and relaxation curves generated by the model, and the features of the evolution of the structuredness under these types of loading are analytically studied. The dependences of these curves on time, shear rate, initial strain and initial structuredness of the material, as well as on the material parameters and function of the model, are studied. Several indicators of the applicability of the model are found which are convenient to check with experimental data. It was examined what effects typical for viscoelastic-plastic media can be described by the model and what unusual effects (unusual properties) are generated by a change in structuredness in comparison with typical stress-strain curves and relaxation curves of structurally stable materials. In particular, it has been proved that stress-strain curves can be both increasing functions and can have decreasing sections resembling a "yield tooth" or damped oscillations, that all stress-strain curves (SSCs) possess horizontal asymptotes (steady flow stress), monotonically dependent on shear rate, and flow stress increases with shear rate growth, that the instantaneous shear modulus, on the contrary, depends on the initial structuredness, but does not depend on shear rate. Under certain restrictions on the material parameters, the model is also capable of providing a bilinear form of stress-strain curves, which is typical for an ideal elastoplastic model, but with strain rate sensitivity. It has been established that the family of stress-strain curves does not have to be increasing either in initial structuredness or in shear rate: in a certain range of shear rates, in which the equilibrium position is a "mature" focus and pronounced oscillations of stress-strain curves are observed, it is possible to intertwine stress-strain curves with different shear rates. It is proved that for any material parameters and functions, all stress relaxation curves decrease and have a common zero asymptote as time tends to infinity. The analysis proved the ability of the model to describe behavior of not only liquid-like viscoelastoplastic media, but also solid-like (thickening, hardening, hardened) media: creep, relaxation, recovery, a number of typical properties of experimental relaxation curves, creep and stress-strain curves, strain rate and strain hardening, flow under constant stress and so on. [ABSTRACT FROM AUTHOR]

• ZK30 Mg alloy after severe friction stir processing, FSP, becomes superplastic. • Grain size distributions are fine, but wide, and prone to instability at high temperature. • Extensive grain coarsening modified conventional strain rate-stress behaviour. • ML ANN model was able to predict superplasticity even with grain coarsening. • ANN model predicts the absence of change in deformation mechanism at high temperature. The aim of this work is to predict, for the first time, the high temperature flow stress dependency with the grain size and the underlaid deformation mechanism using two machine learning models, random forest (RF) and artificial neural network (ANN). With that purpose, a ZK30 magnesium alloy was friction stir processed (FSP) using three different severe conditions to obtain fine grain microstructures (with average grain sizes between 2 and 3 µm) prone to extensive superplastic response. The three friction stir processed samples clearly deformed by grain boundary sliding (GBS) deformation mechanism at high temperatures. The maximum elongations to failure, well over 400% at high strain rate of 10−2 s−1, were reached at 400 °C in the material with coarsest grain size of 2.8 µm, and at 300 °C for the finest grain size of 2 µm. Nevertheless, the superplastic response decreased at 350 °C and 400 °C due to thermal instabilities and grain coarsening, which makes it difficult to assess the operative deformation mechanism at such temperatures. This work highlights that the machine learning models considered, especially the ANN model with higher accuracy in predicting flow stress values, allow determining adequately the superplastic creep behavior including other possible grain size scenarios. [Display omitted] [ABSTRACT FROM AUTHOR]

The superplasticity and microstructure evolution during superplastic deformation for two Al-Cu-Mg-Zr-Mn-Y and Al-Cu-Mg-Zr-Mn-Er alloys were compared. The heterogeneous microstructure was formed in both alloys. Coarse particles of the Cu and Y/Er-bearing and Mn, Fe, Si-bearing phases of solidification origin with a mean size of 1.1/1.4 µm and volume fraction of ~ 9% and fine precipitates of the Mn- and Zr-bearing phases were observed. Precipitates with Zr demonstrated L12 structure and contained Cu, Mg, and Y or Er. The residual elements Si and Fe were found in these precipitates for the alloy with Y. Due to PSN effect of coarse particles and Zener pinning effect of fine precipitates, a fine-grained structure with a mean size of ~ 6.5 µm was formed. Distribution of coarse particles in the aluminum solid solution was more homogeneous for Y-bearing alloy, which exhibited more uniform grain structure and a higher grain size stability with much better superplastic properties. The alloy with Y demonstrated strain rate sensitivity of 0.45–0.55 and elongation to failure of 400–550% at 5 × 10−4–1 × 10−2 s−1 and 575°C. Grain elongation to the tensile direction, dislocation activity in the grain interior and formation of low-angle grain boundaries were observed during superplastic deformation. [ABSTRACT FROM AUTHOR]

The phasing of the friction process provides for the formation of the intersurface phase of the rubbing surfaces of the friction pair, the "third body". In essence, the third body is a hinge of internal friction of a developed stage of joint plastic deformation of surfaces. Being a consequence of the self-organization of surface adaptation processes in the presence of environmental chemistry, the third body can have a wide range of tribological properties. These properties, in turn, are a consequence of the formation of a wide range of optimal (compatible) structures of the third body, which determines the controllability of friction. The relationship of structure and properties as the basic principle of tribomaterial science provokes the question of what are the limits of this relationship? For example, what are the minimum properties of friction and how are they reflected in the essence of the structural structure and behavior of the friction contact? The equation of a quasi-ideal solid third body under friction is obtained, which proves the existence of an elementary structural element of a solid body under friction (deformation), a mechanical (nano) quantum. A mechanical quantum, as an ideal (theoretical) crystal of atomically rough and spherical shape, is an oscillator of dynamic dissipative friction structures. The potential energy accumulated initially during the evolution of contact is further dissipated in the area of compatibility into these formed mechanical quanta of the third body (elementary tribosystem) in the form of surface energy, creating prerequisites for their elastic reversals with an abnormally low coefficient of friction between them. The efficiency of the third body is proportional to the spectrum of elastic reversals of structural shapes. [ABSTRACT FROM AUTHOR]

The superplastic behavior and associated deformation mechanisms of a fine-grained Mg-10.1 Li-0.8Al-0.6Zn alloy (LAZ1011) with a grain size of 3.2 µm, primarily composed of the BCC β phase and a small amount of the HCP α phase, were examined in a temperature range of 473 K to 623 K. The microstructural refinement of this alloy was achieved by employing high-ratio differential speed rolling. The best superplasticity was achieved at 523 K and at strain rates of 10−4 -5 × 10−4 s−1, where tensile elongations of 550–600% were obtained. During the heating and holding stage of the tensile samples prior to tensile loading, a significant increase in grain size was observed at temperatures above 573 K. Therefore, it was important to consider this effect when analyzing and understanding the superplastic deformation behavior and mechanisms. In the investigated strain rate range, the superplastic flow at low strain rates was governed by lattice diffusion-controlled grain boundary sliding, while at high strain rates, lattice diffusion-controlled dislocation climb creep was the rate-controlling deformation mechanism. It was concluded that solute drag creep is unlikely to occur. During the late stages of deformation at 523 K, it was observed that grain boundary sliding led to the agglomeration of the α phase, resulting in significant strain hardening. Deformation mechanism maps were constructed for β-Mg-Li alloys in the form of 2D and 3D formats as a function of strain rate, stress, temperature, and grain size, using the constitutive equations for various deformation mechanisms derived based on the data of the current tests.

The article describes and analyses the changes in the shape of the cantilever made of α-PdHn alloy at a temperature of 240°C with the use of a video recording of the experiment. The experiment is performed for a cantilever made of following alloys: α-PdH0.0105, α-PdH0.0198, α-PdH0.026, α-PdH0.0326, α-PdH0.0464, α-PdH0.0644. The cantilever is covered on one side with a copper film with a thickness of 0.75 μm, which does not allow hydrogen to pass through and does not affect the magnitude of the shape change. Saturation of the palladium cantilever to the α-PdHn alloys is carried out in a chamber at a constant temperature of 240°C. Next, the resulting alloys are kept in isothermal conditions, after which the cantilever is degassed on one side. It is experimentally recorded that, when the pressure changes by ΔРH2 = 0.03, 0.1, 0.15, 0.2, 0.3, 0.43 MPa, the value of the maximum bends for the cantilever increases from -1.6 to -7.05 mm. As established, during the degassing of hydrogen for the cantilever made of α-PdHn alloys, the bend develops in two different time stages. The first stage lasts a very short time (9-15 seconds) and is characterized by the rapid achievement of the maximum bending of the cantilever. The second stage lasts much longer (more than 100 seconds) and is marked by the formation of a plateau and reverse straightening of the cantilever. During the second stage, the cantilever returns to its initial state or reaches a stationary state with minimal deviation from the initial position. As also recorded, the degree of reversibility of cantilever bending during degassing increases with increasing hydrogen pressure. As determined, the internal hydrogen-concentration stresses that arise during degassing of hydrogen from alloys α-PdH0.0105, α-PdH0.0198, α-PdH0.026, α-PdH0.0326, α-PdH0.0464, α-PdH0.0644 exceed the elastic characteristics of gradient alloy α-PdHn (200 MPa) and are in the range from 88 to 539 MPa. The process of formation of the maximum bending of the cantilever in the degassing process for α-PdHn alloys is due to the diffusion transfer of hydrogen, the redistribution of internal stresses in the plate during its bending (straightening) and the corresponding restructuring of the hydrogen-concentration field, which changes the internal conditions of the diffusion transfer of hydrogen into the layers of the α-PdHn alloy. [ABSTRACT FROM AUTHOR]

A homogenized, supersaturated AlZnMgZr alloy was processed via severe plastic deformation (SPD) using a high-pressure torsion (HPT) technique for different revolutions at room temperature to obtain an ultrafine-grained (UFG) microstructure. The microstructure and mechanical properties of the UFG samples were then studied using transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and tensile and hardness measurements. The main purpose was to study the effect of shear strain on the evolution of the microstructure of the investigated alloy. We found a very interesting evolution of the decomposed microstructure in a wide range of shear strains imposed by HPT. While the global properties, such as the average grain size (~200 nm) and hardness (~2200 MPa) appeared unchanged, the local microstructure was continuously transformed. After 1 turn of HPT, the decomposed UFG structure contained relatively large precipitates inside grains. In the sample processed by five turns in HPT, the segregation of Zn atoms into grain boundaries (GBs) was also observed. After 10 turns, more Zn atoms were segregated into GBs and only smaller-sized precipitates were observed inside grains. The intensive solute segregations into GBs may significantly affect the ductility of the material, leading to its ultralow-temperature superplasticity. Our findings pave the way for achieving advanced microstructural and mechanical properties in nanostructured metals and alloys by engineering their precipitation and segregation by means of applying different HPT regimes. [ABSTRACT FROM AUTHOR]

• Superplasticity of fine-grained Mg-10Li alloy was studied. • Severe plastic deformation was used to achieve the fine grains. • Its deformation mechanisms for superplastic flow were analyzed. • Deformation mechanism maps were constructed in 2D and 3D. The superplastic behavior and associated deformation mechanisms of a fine-grained Mg-10.1 Li-0.8Al-0.6Zn alloy (LAZ1011) with a grain size of 3.2 µm, primarily composed of the BCC β phase and a small amount of the HCP α phase, were examined in a temperature range of 473 K to 623 K. The microstructural refinement of this alloy was achieved by employing high-ratio differential speed rolling. The best superplasticity was achieved at 523 K and at strain rates of 10−4 -5 × 10−4 s−1, where tensile elongations of 550–600% were obtained. During the heating and holding stage of the tensile samples prior to tensile loading, a significant increase in grain size was observed at temperatures above 573 K. Therefore, it was important to consider this effect when analyzing and understanding the superplastic deformation behavior and mechanisms. In the investigated strain rate range, the superplastic flow at low strain rates was governed by lattice diffusion-controlled grain boundary sliding, while at high strain rates, lattice diffusion-controlled dislocation climb creep was the rate-controlling deformation mechanism. It was concluded that solute drag creep is unlikely to occur. During the late stages of deformation at 523 K, it was observed that grain boundary sliding led to the agglomeration of the α phase, resulting in significant strain hardening. Deformation mechanism maps were constructed for β-Mg-Li alloys in the form of 2D and 3D formats as a function of strain rate, stress, temperature, and grain size, using the constitutive equations for various deformation mechanisms derived based on the data of the current tests. [ABSTRACT FROM AUTHOR]

This study focuses on investigating the effect of Mg and Si content in different ratios on the microstructure evolution and superplasticity after processing by multidirectional isothermal forging of the Al–Mg–Si–Cu based alloys with additions of Fe and Ni forming large particles of phases of crystallization origin and dispersoid-forming elements Sc and Zr. The study examined alloys with the following Mg/Si content: 1.2/0.4 (3), 1.2/0.7 (1.7), and 2.0/0.7 (2.8) (wt %). The alloys underwent six cycles of isothermal multidirectional forging (MDF) at a temperature of 325°C with cumulative deformation of up to ∑ε = 14.4. During the MDF process, fragmentation occurred in particles of Mg2Si and Al9FeNi eutectic phases, resulting in the formation of particles with sizes of 0.6–0.7 and 1.2–1.5 µm, respectively. Due to particle stimulated nucleation mechanism and suppressed grain growth by nanoscale dispersoids the finegrained structure with a mean grain size of 2 μm was formed in alloys. An increase in Si concentration at constant Mg content, as well as an increase in Mg and Si concentration at a close Mg/Si ratio leads to an increase in fraction of recrystallized grains and a decrease in grain size after MDF. The alloy with the lowest Mg and Si content has shown the highest elongation under superplastic deformation, which is explained by the reduced fraction of Mg2Si phase particles of crystallization origin. [ABSTRACT FROM AUTHOR]

A fine-grained micro-duplex AlCoCrFeNi2.1 eutectic high entropy alloy exhibited high strain rate superplasticity with an elongation to failure of ~ 960 pct at 1173 K and a strain rate of 10-1 s-1. Optimum superplasticity was associated with a strain rate sensitivity of ~ 0.5, and there were transitions to non-superplastic flow with strain rate sensitivities of < 0.5 at both low and high strain rates. Superplasticity is attributed to grain boundary sliding with the observed retention of an equiaxed grain morphology, with some grain growth. Cavities with dimensions in the range of 1 to 5 μm were observed in specimens pulled to failure. Although analysis revealed that cavity nucleation is likely under the experimental conditions, cavity growth was slow because of control by a plasticity growth rate that was proportional to the cavity size. [ABSTRACT FROM AUTHOR]

Microstructure evolution and mechanical properties of Zn-22Al alloy after post-ECAP natural/artificial aging were investigated. A homogenization treatment was applied to the casting samples. In addition, after preparing the samples for the ECAP, secondary homogenization treatment was done and then the samples quenched in the water to form a fine grain structure. After 8 passes of ECAP, some ECAPed samples were naturally aged and some ECAPed samples were artificially aged. Natural aging after 8 passes of ECAP showed that Zn-22Al alloy has a quasi-stable microstructure because limited grain growth occurred. Two-phase structure of Zn-22Al alloy prevented excessive grain growth after natural aging. On the other hand, artificial aging after 8 passes of ECAP caused a relatively much grain growth took place. In shorter times of artificial aging, the grain growth rate is faster due to the high surface energy of grain boundaries. On the contrary, as the time of artificial aging increased, the surface energy of grain boundaries decreased, which leads to a decrease in the grain growth rate. In addition, texture evolution was studied after aging artificial. Therefore, the main texture of α and η phases was determined.

We investigated the effect of C content on the superplasticity of medium Mn steel through high-temperature tensile testing of Fe–7Mn-(0–0.35)C (wt%) steels at temperatures ranging from 490 °C to 720 °C with an initial strain rate of 1.0 × 10−3 s−1. Superplasticity became evident at 550 °C for C-added steels and at 634 °C for the C-free steel. As all the C-added steels exhibited the highest elongation at 650 °C, we conducted in-depth analyses using the specimens tested at 650 °C. The elongation significantly increased with increasing C content up to 0.20 wt%. The results of strain rate sensitivity, apparent activation energy, and microstructural observations indicated that the low elongation of the 0C steel was attributed to the occurrence of dislocation creep, whereas the high elongations of both 0.10C and 0.20C steels were due to the occurrence of grain boundary sliding. The 0.20C steel exhibited higher elongation than the 0.10C steel due to its smaller average grain size and a larger area of α/γ interphase boundaries compared to the 0.10C steel. Meanwhile, the elongation of the 0.35C steel was not significantly improved compared to the 0.20C steel, despite having a smaller average grain size. This was because the 0.35C steel had a lower area of α/γ interphase boundaries, which resulted from the higher γ fraction. We believe the optimal C content for enhancing the superplasticity of Fe–7Mn steel is approximately 0.20 wt%, considering the 0.35C_T steel requires an additional tempering process, and its elongation was comparable to the 0.20C steel.

To explore high temperature ductility, a new Mg-2.70Zn-1.34Y-0.37Ca-0.02Zr (wt.%) alloy has been fabricated by novel multidirectional forging (MDF) and hot rolling. The microstructure and mechanical properties were investigated. The average grain size of MDF + hot rolled alloy is 10.89 ± 0.90 μm refined from the as-cast average grain size of 60.03 ± 0.72 μm. The ultimate tensile strength of 260.51 ± 1.03 MPa, yield strength of 192.29 ± 1.21 MPa, and elongation of 17.83 ± 0.72 % were obtained at room temperature. For high temperature tensile behavior, microstructural examination revealed that continuous dynamic recrystallization and discontinuous dynamic recrystallization are the main softening mechanism in the temperature range of 573–673 K, while dynamic grain growth with bimodal grains and twins is discovered at 723 K in this alloy. X-ray diffraction and scanning electron microscopy –energy dispersive spectroscopy examinations revealed that the constituent phases are composed of α-Mg solid solution and intermetallic compounds of Ca2Mg6Zn3, Mg3YZn6 (I-phase), and Mg3Zn3Y2 (W-phase). The microstructural evolution, such as dynamic recrystallization and dynamic grain growth at desired tensile temperatures, is related to the thermal stability of constituent phases. The elongation to failure of 215.4 % was demonstrated at 673 K and 1.67 × 10−2 s−1, exhibiting high strain rate quasi-superplasticity. A power-law constitutive equation was established. The deformation activation energy of 177.948 kJ/mol and stress exponent of 4.494 revealed that the dominant deformation mechanism of this alloy at elevated temperatures of 573–723 K is dislocation climb controlled by lattice diffusion.

An extruded Mg−6Gd−3Y−1.5Ag (wt%) alloy was processed by 6 passes of equal channel angular pressing (ECAP) at 553 K using route Bc to refine the microstructure. Electron back-scattered diffraction (EBSD) analysis showed a fully recrystallized microstructure for the extruded alloy with a mean grain size of 8.6 µm. The microstructure of the ECAP-processed alloy was uniformly refined through dynamic recrystallization (DRX). This microstructure contained fine grains with an average size of 1.3 µm, a high fraction of high angle grain boundaries (HAGBs), and nano-sized Mg5Gd-type particles at the boundaries of the DRXed grains, detected by transmission electron microscopy (TEM). High-temperature shear punch testing (SPT) was used to evaluate the superplastic behavior of both the extruded and ECAP-processed alloys by measuring the strain rate sensitivity (SRS) index (m-value). While the highest m-value for the extruded alloy was measured to be 0.24 at 673 K, the ECAP-processed alloy exhibited much higher m-values of 0.41 and 0.52 at 598 and 623 K, respectively, delineating the occurrence of superplastic flow. Based on the calculated average activation energy of 118 kJ mol−1 and m-values close to 0.5, the deformation mechanism for superplastic flow at the temperatures of 598 and 623 K for the ECAP-processed alloys was recognized to be grain boundary sliding (GBS) assisted by grain boundary diffusion.

Body-centered cubic refractory metallic materials exhibit excellent high-temperature strength, but often suffer from brittle intergranular fracture due to the recrystallization-induced enrichment of trace elements at grain boundaries (GBs). Here, we report a fully-recrystallized pure molybdenum (Mo) material with room temperature (RT) superplasticity, fabricated by a facile method of powder metallurgy, Y-type hot rolling and annealing. By engineering the ultralow concentration of O at GBs, the inherent GB brittleness of Mo can be largely eliminated, which, in conjunction with high fractions of soft texture and low angle GBs, enables a significant development of ordered dislocation networks and the effective dislocation transmission across low angle GBs. Synergy of these factors greatly suppress the brittle intergranular fracture of Mo, contributing to an enhanced deformability of 108.7% at RT. These findings should have general implication for fabricating a broad class of refractory metals and alloys toward harsh applications. Body-centered cubic refractory metals are known to exhibit excellent high-temperature strength, but often suffer from brittle fracture. Here, the authors produce a bulk pure Mo with stable fine-grain structure after powder metallurgy, Y-type hot rolling and ultra-high temperature annealing (1000~1700 °C) that exhibits room temperature superplasticity. [ABSTRACT FROM AUTHOR]

Microstructure evolution and mechanical properties of Zn-22Al alloy after post-ECAP natural/artificial ageing were investigated. A homogenization treatment was applied to the casting samples. In addition, after preparing the samples for the ECAP, secondary homogenization treatment was done and then the samples were quenched in the water to form a fine-grain structure. After 8 passes of ECAP, some ECAPed samples were naturally aged and some ECAPed samples were artificially aged. Natural ageing after 8 passes of ECAP showed that Zn-22Al alloy has a quasistable microstructure because limited grain growth occurred. The two-phase structure of Zn-22Al alloy prevented excessive grain growth after natural ageing. On the other hand, artificial ageing after 8 passes of ECAP caused relatively much grain growth to take place. In shorter times of artificial ageing, the grain growth rate is faster due to the high surface energy of grain boundaries. On the contrary, as the time of artificial ageing increased, the surface energy of grain boundaries decreased, which led to a decrease in the grain growth rate. In addition, texture evolution was studied after ageing artificially. Therefore, the main texture of α and η phases was determined. [ABSTRACT FROM AUTHOR]

The Zn22Al4Ag alloy was studied to analyze the evolution through plastic deformation and static compression test. First, the master alloy comes from pure Zn, Al, and Ag elements; later, it rolled down to twelve passes. The microstructural characteristics were analyzed by scanning electron microscopy (SEM), Scilab algorithm image processing. Finally, static compression is carried out, including the as-cast, homogenized, and tempered conditions at different loads to measure microhardness. The SEM and XRD image analysis output a 97% plasticity increase in the Zn22Al4Ag alloy due to the rearrangement of the Al, ZnAl, and ZnAg3 phases, observing a phases homogenization from the sixth to the twelfth deformation pass. This deformation allowed the softening of the material as indicated by the microhardness results, relating this behavior to the inverse of the H a l l - P e t c h relationship with hardness. [ABSTRACT FROM AUTHOR]

Abstract—The deformation behavior of an ultrafine-grained (UFG) 08Kh18N10T steel at elevated temperatures (450–900°C) has been studied. The maximum elongation to failure (~250%) is detected at a temperature of 750°C. The deformation of the UFG steel at elevated temperatures is controlled by the intensities of simultaneous processes of grain-boundary sliding and power-law creep. The contribution of each mechanism depends on the grain growth rate under superplasticity conditions, which affects the rate of defect accumulation at migrating grain boundaries. The fracture of the UFG steel has a cavitation character: the fracture and specimen surfaces after high-temperature tests contain large elongated pores having formed on nonmetallic inclusions and submicron pores having formed on σ-phase particles. [ABSTRACT FROM AUTHOR]

In this present work, the AA7075 was selected as matrix material and boron carbide (B4C) particles as reinforced material with several weight percentage of B4C particles (2, 4 and 6) and were prepared by two step stir casting technique to distribute the reinforced particles uniformly in the composite. It is one of the method to increase ductility of the composite is superplastic deformation, to exhibit very large elongation without failure. The basic requirement of fine structure superplasticity is the average grain size of the specimen is less than 10 µm; to achieve this fine grain size through the thermomechanical treatment process includes furnace cooling from the solution treatment to the overaging, warm rolling, recrystallization and aging treatment. The superplastic forming and cavitation behavior of the prepared composite under biaxial stress were investigated under constant forming pressure and temperature of 0.2 MPa and 550 °C, respectively. The formability and cavitation effect of composites were entirely different from the normal superplastic alloys. The yield strength and ultimate tensile strength have reduced drastically after addition of 4% B4C particles the main reason was agglomeration of the ceramic particles. In the superplastic forming process the sample B exhibits very high formability of dome height at 16.5 mm compared to the samples A and C. It is due to the uniform distribution of the particles without agglomeration on the grains as well as along the grain boundaries. [ABSTRACT FROM AUTHOR]

An extruded Mg−6Gd−3Y−1.5Ag (wt%) alloy was processed by 6 passes of equal channel angular pressing (ECAP) at 553 K using route Bc to refine the microstructure. Electron back-scattered diffraction (EBSD) analysis showed a fully recrystallized microstructure for the extruded alloy with a mean grain size of 8.6 µm. The microstructure of the ECAP-processed alloy was uniformly refined through dynamic recrystallization (DRX). This microstructure contained fine grains with an average size of 1.3 µm, a high fraction of high angle grain boundaries (HAGBs), and nano-sized Mg 5 Gd-type particles at the boundaries of the DRXed grains, detected by transmission electron microscopy (TEM). High-temperature shear punch testing (SPT) was used to evaluate the superplastic behavior of both the extruded and ECAP-processed alloys by measuring the strain rate sensitivity (SRS) index (m -value). While the highest m -value for the extruded alloy was measured to be 0.24 at 673 K, the ECAP-processed alloy exhibited much higher m -values of 0.41 and 0.52 at 598 and 623 K, respectively, delineating the occurrence of superplastic flow. Based on the calculated average activation energy of 118 kJ mol−1 and m -values close to 0.5, the deformation mechanism for superplastic flow at the temperatures of 598 and 623 K for the ECAP-processed alloys was recognized to be grain boundary sliding (GBS) assisted by grain boundary diffusion. [ABSTRACT FROM AUTHOR]

The effect of adding a small amount of Ag on the microstructure evolution and superplastic properties of Mg-Y-Er-Zn (WEZ612) alloys was systematically studied. The basal texture of the refined WEZ612 alloy produced by equal channel angular pressing was altered to a non-basal structure upon the addition of Ag. Ag addition also refined the grain size and promoted the formation of a large number of nano-14H-long period stacking ordered phases. Using high-resolution transmission electron microscopy, many nano-precipitated phases were detected on the basal plane of the Mg-Y-Er-Zn-1Ag (WEZ612–1Ag) alloy, The nano-precipitated phases on the basal plane improved the thermal stability of the alloy, lowered the deformation activation energy (Q), and improved the stress sensitivity index (m). At 523 K with a strain rate of 10−2 s−1, the Q value of WEZ612 was higher than that of WEZ612–1Ag (299.14 and 128.5 kJ mol−1, respectively). In contrast, the m value of the WEZ612 alloy (0.16) was lower than that of the WEZ612–1Ag alloy (0.46). At 623 K with a tensile rate of 10−2 s−1, the WEZ612 and WEZ612–1Ag alloys were elongated by 182% and 495%, respectively, with the latter exhibiting high-strain-rate and low-temperature superplasticity. The improved superplasticity of the WEZ612-1Ag alloy is attributed to the nano-precipitated phases, which effectively limit the cavity extension during superplastic deformation. [ABSTRACT FROM AUTHOR]

The structural performance of a novel hybrid dowel, made of a densified wood-filled aluminum tube (DWFAT), for structural timber joints was investigated experimentally, for the first time. Three-point bending tests have been conducted on both hybrid DWFAT dowels and densified wood dowels (DWD) in order to evaluate their strength and stiffness characteristics as well as their ductility and failure modes. The developed hybrid DWFAT dowels were then used and tested in the context of both slotted-in aluminum plate timber and timber-to-timber double shear connections and the obtained load-slip curves as well as the failure modes were analyzed and compared to their equivalent connections made with conventional steel dowels. The results showed that the developed hybrid DWFAT dowel is promising and can be a potential substitute for conventional steel dowels. [ABSTRACT FROM AUTHOR]

Superplastic aluminum (Al) alloys can be used in the forming processes to fabricate complex geometry components for a wide range of applications in the automobile industry, where light weight and high stiffness are needed. Those alloys exhibit extreme tensile elongation of more than 300% at a high homologous temperature and appropriate low strain rate. Superplasticity occurs in Al alloys via the mechanisms of grain boundary sliding, solute drag creep and diffusion creep. Grain boundary sliding usually leads to extensive superplasticity. The activation of grain boundary sliding depends on grain size, strain rate sensitivity, deformation temperature and alloy chemical composition. A complete understanding of influencing factors on Al alloy superplasticity is the key to developing novel superplastic Al alloys. This review discusses the superplastic behavior of several Al alloys, especially focusing on Al-Mg 5xxx alloys. It highlights the mechanisms that govern superplasticity of Al alloys at a low and high strain rate. The factors which influence superplasticity are analyzed. As practice industrial applications, high-cycle-time superplastic forming operations such as quick plastic forming and high-speed blow forming are briefly discussed. [ABSTRACT FROM AUTHOR]

The recently developed process of additive manufacturing of aluminum alloys via laser powder bed fusion (LPBF) has the capability to build parts with complex geometries, which can lead to potential benefits in manufacturing industries. The adoption of intricate thin wall structures is restrained by the lack of reliable mechanical property data and understanding of the failure sequence in extreme cyclic loading conditions. The results show that the LPBF AlSi7Mg thin-walled specimens under an Extreme Low Cycle Fatigue (ELCF) regime for 0.1 mm to 0.8 mm design thin wall thickness variation attained results of 1 to 20 number of cycles to failure (Nf) in as-built, stress-relieved annealing and T5 heat treatment conditions. The present work also explores the factors linking GD&T, and heterogeneity of the thin-walled alternate cyclic bend fatigue-tested specimens. [ABSTRACT FROM AUTHOR]

The auto industry aims to deliver cost-effective, efficient vehicles to meet customer needs. They are utilizing aluminum to lower expenses, enhance durability, and lighten vehicles. Currently, the industry is developing a high-speed blow forming (HSBF) technique--a faster version of the aluminum thermoforming process, superplastic forming (SPF). HSBF allows the rapid creation of aluminum bodywork or structural parts at high temperatures using pressurized gas. It can produce up to 25 parts per hour, significantly faster than SPF, which only produces 4 parts per hour. The primary objective of this project is to select and characterize a seal that can increase the production rate to 120 parts per hour by allowing the sheet to flow into the mold, especially during the initial stages of the forming process, where most of the deformation occurs. Several test benches were developed to assess the performance and durability of the selected high-temperature seals under conditions that imitate the HSBF process. During the tests, low air pressures are applied to a gasket-enclosed cavity and the resulting mass-flow leakage is measured. The temperature of the mold is kept constant at approximately the superplastic temperature of the aluminum alloy. Through testing, we derived leakage mass flow curves based on cycle count, showcasing the superior sealing ability and longevity of packing seals in HSBF conditions. The seals displayed good durability and sealing performance under HSBF operational conditions, sustaining over 3000 cycles. Moreover, the seals attained a leakage mass flow rate of around 0.3 g/s•m•bar, nearly ten times below the target application limit of 2 g/s•m•bar, confirming their superior performance. [ABSTRACT FROM AUTHOR]

Superplastic aluminum forming is a promising manufacturing process for the transportation industry because it allows for the manufacturing of complex body parts from a single sheet of aluminum, reducing the number of pieces and the weight of vehicles. However, the process is still limited, among other things, by the low heating rate of the sheets. Indeed, for the 5000 series aluminum alloy, a temperature between 450 and 550 °C must be reached, but the furnaces used are inefficient, leading to heating times in the order of ~3 to 6 min. A test bench has been developed to evaluate direct resistance heating as a solution. It allows heating 350 x 200 x 1 mm sheets. The uniformity of the sheet's temperature is an important factor in ensuring good formability and has been evaluated using an infrared camera. Tests show that the sheets can be heated within 20 s using a current of 6200 A, with a standard deviation of about 10 °C over the surface of the sheet. [ABSTRACT FROM AUTHOR]

A theoretical study of the phenomenon of the superplasticity of metallic materials is carried out. Numerical calculations are performed on the basis of a two-level finite-element model of an elastic–plastic medium. The plastic properties of the deformable-medium element, at which deformation by uniaxial tension in the superplasticity mode occurs, are found. It is shown that depending on the shape of the stress–strain curve (σ–ε) of the medium element, various types of plastic-flow localizations are observed at the macroscale level. The nonmonotonic dependence σ–ε of a deformable-medium element with a single maximum is determined as the condition for the appearance of a stable necking. In the case when the dependence σ–ε, which is characterized by the hardening of the elementary volumes, has two maxima, a propagating (running) neck is observed, then a second (counter) neck appears, while further tension leads to the appearance of a third stable neck in which fracture occurs. In the case of a more complex oscillating shape of the σ–ε curve, multiple propagating necks are observed. The movement of multiple necks propagating along the sample leads, ultimately, to a uniform pattern of deformation and makes it possible to achieve the strain values observed in the superplasticity mode. [ABSTRACT FROM AUTHOR]

Superplastic forming (SPF) is a material forming technique that uses superplastic exceptional elongations and deformation characteristics to form superplastic materials into certain shapes. The combination of superplastic forming with diffusion bonding (SPF/DB) gives rise to an almost unlimited extension of superplastic forming since more integral lightweight cellular structural components can be manufactured. This paper discusses numerical modelling of the mechanism of superplasticity in metallic materials. The SPF computational method based on the finite element technique augmented with the controlling rate of deformations is developed to examine a range of design or operating conditions leading to more economical forming processes. The non-Newtonian 'viscous flow' material is used to model the constitutive of superplastic material during the forming period. The contact mechanics between the sheet material and the mold surface and the intersheet material contact mechanics are imposed using the penalty control method, in which the sticking contact boundary conditions are employed. The space discretization is carried out using the membrane element under plane strain and axisymmetric flow stress conditions, while the implicit time integration technique is utilized to follow the shape changes of the formed sheet material. The validation of the SPF finite element formulation was performed by comparing it with the available analytical solution of Hydraulic Free Bulging of Thin strips. The SPF of a hemispherical dome made of 7475 aluminum sheet alloy was performed to demonstrate the forming process as well as to validate the results obtained between the SPF finite element numerical simulation and the experimental results. The SPF/DB of the multicell component section is considered in the final part. [ABSTRACT FROM AUTHOR]

Double-pass friction stir processing (FSP) engendered intense plastic deformation in Mg–3Al–1Zn alloy with variation in the most influential process parameters, namely tool rotation speed and tool traverse speed. The effect of change in the FSP processing route on the resulting grain size was also analysed. Uniformly distributed fine equiaxed grains (average grain size ∼ 6.15 μm) were acquired in the stir-zone (SZ) due to extensive dynamic recrystallization (DRX). Attainment of large grain refinement encouraged for further investigation of the alloy's superplastic behaviour at elevated temperatures. Microstructural examination was followed by uniaxial tensile tests that were carried out at three distinct temperatures of 350, 400 and 450 °C at the constant strain rate of 1.3 × 10−3 s−1. With the rising deformation temperature, reduction in the flow stress led to significant increase in the tensile elongations of all the processed specimens. Micro-grain superplasticity (elongation >200% under tension) was observed at the highest deformation temperature for the friction stirred specimen with the finest grains.

Superplastic tensile test was performed on a β-rich α+β titanium alloy (SP700 alloy) sheet in the temperature range of 740–800 °C and strain rate range of 1 × 10−4-1 × 10−2 s−1. The effects of the deformation parameters on the flow curves, strain rate sensitivity (m-value), thermal activation energy (Q-value) and microstructural characteristics were investigated to elucidate the deformation mechanism. The results showed that the examined SP700 alloy exhibited excellent superplasticity with fracture elongation up to approximately 1800% deformed at 760 °C and 1 × 10−3 s−1, with the maximum m-value of 0.55. The shapes of the flow curves were dependent on the strain rate and showed a type of curves without an obvious steady-state flow at relatively high strain rates. For this β-rich α+β titanium alloy, when deformed at 740–780 °C and medium strain rates (approximately 5 × 10−3-5 × 10−4 s−1), the controlling deformation mechanism was the grain boundary sliding accommodated by dislocation slip. When deformed at 800 °C and a strain rate of 1 × 10−4 s−1, m-value decreased to 0.1 and the main deformation mechanism was dislocation slip with a high β volume fraction over 50% and average grain size over 5 μm. Meanwhile, the dominant texture changed from to or because of the grain rotation caused by the grain boundary sliding.

Borides are usually hard and brittle materials; however, we report the synthesis of superplastic nanostructured NdB6 ceramic powders, counter to the conventional wisdom that borides are always brittle. We investigate that through strain engineering, NdB6 can be made extremely ductile if the lattice is compressively strained and highly defected, based on transmission electron microscopy (TEM) and density functional theory (DFT) calculations. In this study, the synthesis conditions were designed based on CALPHAD modelling, and the superplastic NdB6 powders were successfully obtained through mechanochemical synthesis (MCS) of Nd2O3, B2O3 and Mg initial materials in a high-energy ball mill. Following MCS, the powders were purified in a hydrochloric acid (HCl) containing aqueous solution in order to leach out MgO by-product. The purified powders were characterized using X-ray diffractometry (XRD), Helium (He) gas pycnometry, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), particle size analysis (PSA) and magnetometry techniques, which demonstrated NdB6 nanoparticles with an average particle size of 118 nm belonging paramagnetic behavior at cryogenic temperatures. DFT calculations have been carried out through to investigate the structural, mechanical, electronic, optical, thermodynamic and magnetic properties of NdB6. The impact of various defects was examined, which revealed the significance of boron vacancies and compressive strains in the superplastic form of NdB6.

Experiments were conducted to assess the effect of processing temperature on the hardness evolution, microstructure and the flow properties of an annealed Al–3Mg alloy processed by high-pressure torsion (HPT) at either 300 or 450 K. The results demonstrate that HPT processing at room temperature (RT) leads to higher microhardness values with a more uniform hardness distribution in the Al alloy compared with processing at 450 K. After 10 HPT turns at RT, the microstructure displayed a more intense grain refinement, a higher dislocation density and smaller Al3Mg2 precipitates than after HPT at 450 K. Accordingly, the metal processed at RT showed enhanced strength at RT and consistently exhibited superplastic flow during deformation at 523 K, with tensile elongations of ∼530–650% for strain rates from 10−3 to 10−2s−1. Conversely, a maximum elongation of ∼110% was recorded at 523 K in the alloy processed by HPT at 450 K. This behaviour is attributed to an enhanced thermal stability in the metal processed at RT compared with HPT at 450 K where deformation at 523 K led to the onset of abnormal grain coarsening due to a more disperse distribution of grain sizes and the partial dissolution and coalescence of Al3Mg2 precipitates after HPT processing.

In this work, the thermoplasticity of hot extruded (HEXed) FGH4096 superalloy was greatly enhanced by sub-solvus temperature holding followed by extremely slow cooling (S-ESC). After S-ESC processing, the dispersed fine γ′ precipitates inside the grains and grain boundaries obviously grow up. Under most deformation conditions, the S-ESCed samples exhibit smaller flow stress and larger strain rate sensitive index (m) values than the HEXed samples, especially the peak value of m is 0.75 vs. 0.32. This is because fine γ′ precipitates limit deformation by pinning dislocation, and coarse γ′ precipitates promote dynamic recrystallization (DRX). Under the high strain rate of 1 s−1, the DRX degree of the HEXed sample is greatly affected by temperature, while the S-ESCed samples maintain a high DRX degree at different temperature. At the high temperature of 1100 °C, the S-ESCed samples exhibit smaller grain sizes and higher DRX degrees than the HEXed sample under low strain rates. More importantly, because the γ′ precipitates promote DRX, the S-ESCed sample achieves superplasticity at 1090 °C and 10−3 s−1.

Superplasticity of a coarse-grained cast Mg–2.5Gd–0.5Zr alloy was investigated by assessing the strain rate sensitivity index (m-value) through the shear punch testing (SPT) method in the temperature range of 623–748 K and shear strain rate range of 2.8 × 10−3–2.2 × 10−2 s−1. The initial as-cast grain size of about 150 μm was reduced to about 3.5 μm at the end of the test. This severe grain refinement caused by dynamic recrystallization (DRX) facilitated superplasticity in the studied cast alloy. According to the respective m-values of 0.51 and 0.53 obtained at 698 and 723 K, and the activation energy of 80 kJ mol−1, the prevailing mechanism of deformation was suggested as grain boundary sliding (GBS) controlled by grain boundary diffusion.

Shaping of dense ceramics is difficult due to their inherent brittleness. Nanograined ceramics like tetragonal zirconia (TZP) can be superplastically deformed and shaped at high temperatures owing to grain boundary sliding (GBS). Herein, the enhanced plasticity of gadolinium‐doped ceria (GDC) ceramics under mild and strong AC electric current in terms of steady state creep rate under both compressive and tensile loading is demonstrated. A current density of 25 and 200 mA mm−2 is used for the creep deformation. The creep rate increases by up to two orders of magnitude under electric current. The stress exponent remains unchanged for creep experiments at 1200 °C with and without electric current, suggesting a GBS mechanism of plastic deformation in both cases. The field‐enhanced creep rate is attributed to the interaction of space–charge layer and the electric field resulting in enhanced GBS. A higher current density results in enhanced ductility of GDC even when the Joule heating effect is compensated by reducing the furnace temperature. [ABSTRACT FROM AUTHOR]

Double-pass friction stir processing (FSP) engendered intense plastic deformation in Mge3Ale1Zn alloy with variation in the most influential process parameters, namely tool rotation speed and tool traverse speed. The effect of change in the FSP processing route on the resulting grain size was also analysed. Uniformly distributed fine equiaxed grains (average grain size ~ 6.15 mm) were acquired in the stir-zone (SZ) due to extensive dynamic recrystallization (DRX). Attainment of large grain refinement encouraged for further investigation of the alloy's superplastic behaviour at elevated temperatures. Microstructural examination was followed by uniaxial tensile tests that were carried out at three distinct temperatures of 350, 400 and 450 °C at the constant strain rate of 1.3 ° 10-3 s-1. With the rising deformation temperature, reduction in the flow stress led to significant increase in the tensile elongations of all the processed specimens. Micro-grain superplasticity (elongation >200% under tension) was observed at the highest deformation temperature for the friction stirred specimen with the finest grains. [ABSTRACT FROM AUTHOR]

The influence of nickel on superplasticity characteristics, microstructure evolution and the contribution of acting superplastic deformation mechanisms in the Al–Zn–Mg–Cr based alloys has been studied. In the Al–Zn–Mg–Cr alloy, dispersoids with an average size of 140 nm containing aluminum, chromium, magnesium, and a small amount of zinc are precipitated. In the Al–Zn–Mg–Cr–Ni alloy, additionally an Al3Ni phase has formed. Nickel aluminide provides a more homogeneous and stable grain structure at elevated annealing temperatures and during superplastic deformation at 440°C. An alloying with Ni reduced the average grain size from 7.7 to 7.3 μm before deformation and from 10 to 8.6 μm after straining to 0.69. An increased dislocation density has been found near the Al3Ni particles after deformation. At comparable values of the strain rate sensitivity coefficient (m ≈ 0.6), the presence of Al3Ni particles results in a higher contribution of GBS, and a lower contribution of intragranular dislocation slip, as compared to the alloy without these particles. The alloying with Ni provided a more equiaxed fine-grained structure and an increase in elongations-to-failure. [ABSTRACT FROM AUTHOR]

Homogeneous nanostructured and ultrafine grained (NS, UFG) states with mean grain sizes of 95 and 200 nm, respectively, have been formed in a 1565ch Al–Mg alloy (Al–5.66Mg–0.81Mn–0.67Zn–0.09Zr–0.07Cr–0.04Ti–0.001Be–0.3(Fe + Si) wt %). Microstructure of both states is represented by grain boundaries with predominantly high-angle misorientations. The alloy, produced both by high pressure torsion at room temperature and equal channel angular pressing at 200°C using the Conform approach, exhibits superplasticity at low temperatures in the range 250–300°C and strain rates in the range of 5 × 10–4–10–2 s–1. Elongation values range 170–560%, while the rate sensitivity coefficient (m) varies from 0.3 to 0.73 at low flow stress for both NS and UFG structures. The temperature range for the stability of strength properties of the 1565ch alloy in NS and UFG states after thermal and thermal mechanical treatments has been determined. The material in both structural states maintains a high level of strength after undergoing deformation under SP conditions. The deformation relief formed on the gage surface of the NS and UFG specimens of the 1565ch alloy during the established SP yield stage has been analyzed. [ABSTRACT FROM AUTHOR]