Plastic Deformation Process Research Articles

MECHANISM OF FORMATION OF INTERNAL AND SURFACE DEFECTS IN CASTING AND THEIR TRANSFORMATION INTO SURFACE DEFECTS OF SHEET

This study aimed to elucidate the formation mechanisms of micro-macrostructural heterogeneities in the ingot's cortical zone and their transformation into surface defects during heating, plastic deformation, and rolling processes. The methodology and results of studying the macro-and microstructural and chemical heterogeneities of ingots and finished rolled sheets are presented. A comparative method of structural-concentration analysis of metal at theend-to-end metallurgical processing stage of ingot -slab -rolled sheets was developed. The technique utilizes metallographic methods to study the structure and perform qualitative analysis of non-metallic inclusions. The research findings indicate that the quality of the rolled sheet surface is predominantly determined by the physical heterogeneity of the ingot's crust zone, while the internal defects in thin rolled sheets are largely influenced by the contamination of the metal with non-metallic inclusions. A novel mechanism is proposed for the transformation of defects in the casting cortical zone into surface and internal defects in rolled sheets. This study contributes to a deeper understanding of the formation and transformation of defects during metal processing, enabling the development of strategies for improving the quality of rolled sheets. Additionally, the study highlights the importance of controlling the physical heterogeneity of the ingot's crust zone and minimizing non-metallic inclusion contamination to achieve high-quality rolled sheets.

Coupled effect of prestrain and intermediate annealing on mechanical properties and microstructural evolution of GH5188 superalloy

The forming of sheet metal parts with complex structures often requires multiple processing. The Co-based superalloy GH5188 sheet is taken as the research object for two-stage uniaxial tensile experiments including intermediate heat treatment, where the prestrain is 10%, 20% and 30%, respectively, in the first stage. The results indicate that the macroscopic residual stress increases with increasing prestrain, which is manifested as the increase of the initial yield strength, the deterioration of ductility and work hardening ability. The increase in dislocation density in the plastic deformation process is the decisive factor. After annealing, the number of deformed grains greatly reduces, and the grain size is refined, resulting in a corresponding reduction in dislocation density. Intermediate heat treatment can eliminate dislocation stacking and stress concentration in the alloy and reduce the influence of internal stress generated during work hardening. Furthermore, the intermediate annealing can decrease the initial yield stress and increase the elongation of the predeformed sheet, while retaining desirable work hardening ability and tensile strength, ultimately enhancing the subsequent work performance.

Determination of Limiting Deformations at Testing Cylindrical Samples for Tension

This paper proposes a method for calculating limiting deformations under conditions of localized deformation during tensile testing. The method for calculating limiting deformations was used to construct plasticity diagrams under conditions of strain localization under uniaxial tension.
 The plasticity diagram is one of the material functions that forms the technological map of the material. The plasticity diagram displays the properties of a material depending on the degree of deformation and the stress state scheme.
 According to the studies carried out in this work, it was established that the critical increase in plasticity with increasing stress state indicator is explained by the influence of three factors: the strain gradient, the history of deformation and the third invariant of the stress tensor.
 The obtained dependencies make it possible to construct plasticity diagrams for materials whose destruction is preceded by localized deformation in the form of a "neck".
 This work establishes the quantitative influence of these three factors on the magnitude of the limiting deformations of a sample stretched to the point of failure.
 Application plasticity diagrams constructed using the proposed methods for cold plastic deformation processes, depending on the type of deformation path and the features of metal rheology, clarifies the value of the used plasticity resource of the metal, which allows to reduce the number of defective products for processes whose modes are calculated according to limit deformations.

Enhancement of the Microstructure and Fatigue Crack Growth Performance of Additive Manufactured Titanium Alloy Parts by Laser-Assisted Ultrasonic Vibration Processing

Post-processing techniques can efficiently improve the surface quality, address microstructural defects, and optimize mechanical properties in additively manufactured parts. Surface severe plastic deformation processes such as ultrasonic nanocrystal surface modification (UNSM) integrated with localized laser heating were explored to enhance the surface properties, microstructure as well as the fatigue crack growth properties (FCG) in both directions of built. We successfully induced greater plasticity flow and achieved beneficial refinement of the surface grain structure by precisely controlling the heat and impact energies during surface treatment process. The LA-UNSM process, with the parameters utilized in this study considerably decreased the FCG rates of treated samples, when compared to samples without surface treatment. Improved fatigue crack growth properties along vertical and horizontal orientations after the post-process treatment were attributed to the induced-microstructural changes, improved surface quality, induced compressive residual stresses through gradient structure deformation layer that was prepared on the surface of the material. The fractographic analysis revealed that the cracks mostly originated from the pores in the as-produced state. This observation shows a clear correlation between the surface treatment performed and a substantial improvement in fatigue crack growth resistance.

Hot deformation behavior and microstructure evolution of TC11 dual-phase titanium alloy

Thermomechanical processing is one of the major steps in the fabrication of structural components used in various engineering applications. The thermomechanical coupling effect of temperature and strain rate has a significant impact on the stress-strain thermal deformation behavior of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si (TC11) alloy. Here, the hot deformation behavior of TC11 dual-phase alloy has been comprehensively investigated by the hot compression tests with deformation temperatures ranging from 870 °C to 960 °C and strain rates of 0.01 s−1 to 1 s−1. Based on the flow stress curves and Arrhenius-type constitutive equation, a strain compensated Arrhenius model for TC11 alloy was successfully developed, achieving rapid and accurate prediction of high-temperature flow stress. By studying the deformed microstructure characteristics of materials under various deformation conditions, the role of deformation temperatures and strain rates was fully discussed in microstructure evolution, including the primary α phase (αp) and lamellar (αs). The thin-long lamellar shape αs can be obtained at a higher strain rate and deformation temperature. The predominance of single-peaked stress features in most flow curves, along with EBSD characterization results, indicates that continuous dynamic recrystallization (DRX) is the primary softening mechanism under different deformation conditions. This work supports the rapid prediction of flow stress and the relationship between process parameters and microstructural evolution to expedite the design optimization of plastic deformation process parameters and the development of advanced TC11 titanium alloy with targeted microstructures.

Enhanced Microhardness and Corrosion Performance of Additively Manufactured Inconel 718 Specimens through Nanostructuring by Severe Plastic Deformation

Severe plastic deformation (SPD) processes, particularly high-pressure torsion (HPT) have been increasingly applied to metallic specimens fabricated by laser powder bed fusion (L-PBF) additive manufacturing (AM) for enhancing their mechanical and functional properties through nanoscale grain refinement (≤ 100 nm). In this study. L-PBF AM-fabricated Inconel 718 (IN 718) specimens are initially subjected to 10 HPT revolutions to produce nanosized grains. Subsequently, microstructural characterisation, as well as hardness and electrochemical tests are conducted to evaluate the evolution of microstructures, hardness, and corrosion performance of the as-received and HPT-processed specimens by using various microscopy, Vickers microhardness (HV) measurements, and corrosion performance, respectively. The results reveal an average grain size of ~ 46 nm, dense dislocation networks, and nanotwins after 10 HPT processing, which contribute to the two-fold hardness increase compared to the as-received condition. Such microstructures also contributed to the overall improved corrosion performance after 10 HPT processing, as quantified by the 83% and 73% reduction in corrosion rate and pitting potential, respectively.

Atomistic modeling of idealized equal channel angular pressing process

Severe plastic deformation (SPD) processes are forming techniques that impose large plastic strains to achieve ultra-fine grained and nanocrystalline microstructures. The refined microstructure results in a significant increase in strength and in many cases without a considerable loss in ductility. Despite their long existence, a comprehensive understanding of the deformation and grain refinement mechanisms during SPD is still lacking. Atomistic simulations that are regularly used to obtain insights into material behavior have rarely been used to study SPD processes. In this work, we use large scale atomistic simulations of the molecular statics/dynamics kind to model the equal channel angular pressing (ECAP) process, a specific SPD process. Three different materials—Al, Ni and Cu—are used to model high, medium and low stacking fault energy materials. Large simulation cells are used to facilitate grain refinement at the nanoscale. The simulations are carefully analyzed in terms of stress–strain behavior, dislocation activity and grain refinement. All samples show the formation of deformation twins at the nanoscale, which generally detwin at increased strains via dislocation twin interactions. A significant number of stair-rod dislocations form via dislocation–dislocation interactions and are present at low angle grain boundaries in the early stages of deformation. Such stair-rod dislocations also result in the formation of stacking fault tetrahedra which are present in significant numbers in all samples. Finally, difficulties in studying grain refinement at very large strains in atomistic simulations are discussed.

Research on incremental forming simulation based on an improved constitutive model

The incremental sheet metal forming process, characterized by the step-by-step deformation of sheet metal using a simple die, is classified as a type of plastic deformation technology. This method allows for the formation of complex-shaped parts even without the use of a specialized die. Its notable characteristic lies in its low forming load and high flexibility. To accurately forecast finite element simulation outcomes for the incremental sheet forming of 2024-O aluminum alloy sheets, constructing a precise constitutive model is essential. Typically, the uniform strain range in traditional unidirectional tensile tests does not surpass 0.3, primarily due to the necking phenomenon. This limitation hampers the accurate prediction of the actual large plastic deformation process. To address this issue, a theoretical model describing the stress-strain relationship in metal plastic deformation processes is developed using crystal plasticity theory. The constitutive model for the forming of 2024-O aluminum alloy is then constructed by adjusting the hardening coefficient and hardening index. Utilizing the improved constitutive model, the incremental sheet forming process is simulated using ABAQUS software. Upon comparison with experimental results, it is observed that the Thickness Average Absolute Relative Errors (TAARE) of the adjusted constitutive model at forming angles of 60°, 55°, and 50° are 0.414%, 0.467%, and 0.256%, and The Thickness Root Mean Square Errors (TRMSE) are determined as 0.0121, 0.0116, and 0.0094, respectively. These results indicate that the constitutive model and parameters established in this study can adequately capture the mechanical behavior of 2024-O aluminum alloy during the incremental sheet forming process.

Magnetic Shape Memory Nanocomposites Assembled with High Speed High Pressure Torsion.

When a severe plastic deformation (SPD) process is performed at high temperatures, it becomes more versatile. Designed originally for the bulk nanoconstruction of hard-to-deform alloys, high-speed high-pressure torsion (HSHPT) is an SPD method used in this research for assembling multiple layers of shape memory nanocomposites. Three hard-to-deform magnetic alloys in the cast state were used. Soft magnetic shape memory alloys, NiFeGa and FePdMn, and a potentially hard magnetic alloy, CoZr, were assembled in various composites. Both grain refinement and strong layer bonding were achieved in ZrCo/FePdMn and ZrCo/NiFeGa composites in seconds. The very short SPD time is specific to HSHPT because of the intense friction that occurs under high pressures, which generates huge amounts of heat. After SPD, the temperature rises in bulk material like a pulse, being dissipated mostly through heat conduction. The SPD parameters were carefully controlled with an advanced automation system using a programmable logic controller. Nevertheless, the major drawbacks of high-pressure torsion were overcome, and large SPD discs were obtained. Various investigation techniques (optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and atomic force microscopy) show well-defined interfaces as well as a fine and ultrafine structure.

Effect of Manganese on the Strength-Toughness Relationship of Low-Carbon Copper and Nickel-Containing Hull Steel.

The influence of varying the manganese (Mn) contents of high-strength copper-containing hull steel on its microstructural evolution and mechanical properties was investigated. With increasing Mn content from 2 to 5%, the tensile strength of the steel increased by ~100 MPa, while the elongation of steel remained at ~23.5%, indicating good plasticity. However, the 2Mn sample had 128 J higher low-temperature (-84 °C) impact work than the 5Mn sample. The microstructures of different Mn steels were composed of fresh martensite (FM), ferrite/tempered martensite (F/TM), and reversed austenite (RA). The increase in Mn content markedly increased the presence of RA and intensified the work hardening caused by the transformation-induced plasticity (TRIP) effect during the tensile process. However, as the phase transformation in different Mn steels occurred in the early stage of strain and did not extend throughout the entire plastic deformation process, increasing plasticity via phase transformation was difficult. In addition, although the volume fraction of RA increased significantly in 4Mn and 5Mn steels, the stability of RA significantly decreased. The presence of numerous metastable blocks and coarse lath-like RA contributed little to low-temperature impact work and was even detrimental to toughness. The substantial fresh martensite resulting from phase transformation facilitated microcrack generation, owing to rapid volume expansion and mutual impacts, thus reducing the work required for crack formation. Additionally, the abundance of deformation twins significantly reduced the work needed for crack propagation. These combined actions significantly reduced the low-temperature toughness of 4Mn and 5Mn steels.

Experimental and Numerical Study of Forming Limit in 1060 Aluminum Ultrasonic Vibration Single Point Incremental Forming

Low formability, low productivity and forming quality are the main factors restricting the industrial application of single point incremental forming technology. Ultrasonic vibration was introduced into the single point incremental forming process to improve the forming limit of sheet metal by changing the deformation mechanism of material. A device combining ultrasonic vibration with plastic deformation processing technology and single point incremental forming was developed in this work. Taking cone parts of 1060 aluminum as the research object, the effects of ultrasonic vibration amplitude and frequency on equivalent stress and equivalent plastic strain in forming process were analyzed by combining numerical simulation and experimental research. Then, the forming angle of cone parts was used as the standard to study the influence of ultrasonic vibration parameters on formability. The results show that the equivalent stress decreased and equivalent plastic strain increased by superimposing ultrasonic vibrations, ultrasonic vibration can significantly change the formability and improve the forming limit of 1060 aluminum, the forming limit of 1060 aluminum can be maximized by selecting ultrasonic vibration parameters: amplitude 0.03 mm and frequency 30 kHz.

Optimization of the Mechanical and Corrosion Resistance of Alloy 625 through Aging Treatments

In the as-annealed condition, the nickel-based Alloy 625 has excellent mechanical and corrosion properties compared to those of common stainless steels. This peculiarity enables its exploitation in several industrial fields at cryogenic and high temperatures and in the presence of severely corrosive atmospheres. However, in this alloy, when high-temperature plastic deformation processes and heat treatments are not carefully optimized, the occurrence of excessive grain coarsening can irremediably deteriorate the mechanical strength, possibly leading to incompatibility with the standard requirements. Therefore, this research work investigated the possibility of adopting single- and double-aging treatments aimed at improving such strength loss. Their optimization involved identifying the best compromise between the hardening effect and the loss in corrosion resistance induced by the simultaneous formation of intergranular chromium-rich carbides during aging. The investigation of the aging treatments was performed using hardness, tensile and intergranular corrosion tests considering different time–temperature combinations in a range from 621 °C to 732 °C. Double aging resulted in a considerable acceleration in the hardening response compared to single aging. However, even after its optimization in terms of both temperature and time, the intergranular corrosion resistance remained a critical aspect. Among all the tested conditions, only single aging at 621 °C for 72 h was acceptable in terms of both mechanical and corrosion properties. The influence of longer exposures will be investigated in a future study.

Microstructures and mechanical properties of a γ-TiAl alloy modified by Gd additions

The microstructural evolutions and room-temperature tensile properties of Ti-45Al-2.5Nb-1.5Mo-(0-0.2)Gd were investigated in details. Experimental result revealed that there were precipitated particles, involving Gd2TiO5 and GdAl3, distributing within the microstructure of the Gd-containing TiAl alloys, and the increase in the Gd addition resulted in the aggregation of Gd-containing particles, forming a network structure along grain boundary and colony boundary. The addition of Gd also had a significant refining effect on the average inter-lamellar spacing. The ultimate/yield strength and elongation increased first and then decreased with the content of Gd. Gd addition did not change the mixed fracture mode of crack propagation along and across the lamellae. In the plastic deformation process of Gd-containing sample, except for dislocation gliding, twinning-controlled deformation mode occurred, contributing to the improvement of mechanical properties. Moreover, dislocations could directly cut through the small-size Gd-containing particle, while some dislocations would continue to slip via bypassing the large-size Gd-containing particle.

Elastic Shakedown and Roughness Evolution in Repeated Elastic–Plastic Contact

Surface roughness emerges naturally during mechanical removal of material, fracture, chemical deposition, plastic deformation, indentation, and other processes. Here, we use continuum simulations to show how roughness which is neither Gaussian nor self-affine emerges from repeated elastic–plastic contact of rough and rigid surfaces on a flat elastic–plastic substrate. Roughness profiles change with each contact cycle, but appear to approach a steady-state long before the substrate stops deforming plastically and has hence “shaken-down” elastically. We propose a simple dynamic collapse for the emerging power-spectral density, which shows that the multi-scale nature of the roughness is encoded in the first few indentations. In contrast to macroscopic roughness parameters, roughness at small scales and the skewness of the height distribution of the resulting roughness do not show a steady-state. However, the skewness vanishes asymptotically with contact cycle.Graphical

Mathematical Methods of Observation of Wave Processes During Deformation of 3D Technology Products

The purpose of this work is to develop and apply mathematical methods (Fourier interpolation) to fix the presence and evaluation of the mechanisms of wave processes developing in products made of powder stainless and heat-resistant alloys of additive technologies (SLM) during their deformation.Methods. To fix the presence of wave processes of plastic deformation in loaded 3d technology products, samples of powder stainless steel 03X18H12M2 (analog AISI 316L) and powder heat-resistant alloy 08ХN53BMTU (analog Inconel 718), manufactured using SLM technology on a 3d printer SLM280 2.0HL, were used. The samples were subjected to uniaxial stretching (GOST 1497-84) with a constant rate of capture in air at room temperature. The lengths of the marked sections were measured using digital video recording of the loading process of the marked surface of the samples. Graphs of the dependences of local relative deformation along the length of the sample and at selected test moments were constructed. The mathematical substantiation of the existence of the wave character of the fixed functions as periodic was carried out by decomposing them into a Fourier series with subsequent interpolation.Results. It has been experimentally established that in the volume of the studied samples of powder stainless steel type 316L and heat-resistant alloy type Inconel 718, obtained by SLM technology, when they are stretched, there is a multistage character of wave deformation reflecting the development and movement of local micro-volumes of increased plasticity (foci of localized deformation). The Fourier interpolation procedure of a complex of experimentally obtained piecewise linear functions of the dimensions of the marking grid and their local deformations confirmed their apparent periodicity, i.e. the presence of a wave character.Conclusion. The developed technique of fixing and mathematical processing of wave deformation spectra can be used to analyze the changing parameters of the surface marking (rolling grid) of 3d products both along their length and at fixed loading times, as well as when constructing multidimensional dependencies of the marking parameters on the geometry of samples and test time.

Anisotropic and heterogeneous acoustoplasticity of α-Ti during ultrasonic vibration assisted compression: Modeling and experiments

Introducing ultrasonic vibration (UV) into the plastic deformation process is a promising and efficient way to improve the formability of metallic materials. However, the acoustoplasticity of α-Ti with pronounced anisotropic behavior during UV-assisted deformation is still not well understood, and the underlying mechanisms associated with the ultrasonic effect on multiple slip/twinning systems remain ambiguous. In this research, the anisotropic and heterogeneous acoustoplasticity of α-Ti was investigated through modeling and experiments. A novel acoustic crystal plasticity model considering the anisotropic ultrasonic response of multiple slip/twinning systems was proposed, in which the ultrasonic softening is determined by the coupling effect of crystal orientation, mechanical threshold, and ultrasonic energy density. The proposed model was validated through the mechanical response of the UV-assisted compression and the twin volume fraction of α-Ti specimens along RD, TD, and ND directions. Full-field crystal plasticity simulations regarding UV-assisted compression were carried out. Then the mechanism of the acoustoplasticity of α-Ti was explored via the analysis of ultrasonic activation on multiple slip/twinning systems and the grain scale deformation behavior. A considerable anisotropic and heterogeneous ultrasonic softening effect of α-Ti was found, and the anisotropy as well as the magnitude of ultrasonic softening increase with the ultrasonic energy density. The ultrasonically activated deformation modes gradually change from prismatic slip and tensile twinning to basal slip and compressive twinning from RD, TD to ND specimens, which results in a higher average CRSS decrease and more pronounced ultrasonic softening macroscopically. The grain scale stress inhomogeneity of α-Ti is relieved under UV, and the local deformation and grain rotation are both enhanced. The dislocation motion and twinning behavior are both promoted by UV. The facilitated twinning behavior can be attributed to the enhanced dislocation assisted nucleation and propagation of deformation twins under UV. These findings provide a fundamental understanding of the anisotropic and heterogeneous acoustoplasticity of α-Ti during the UV-assisted deformation process.

Kinematic Characteristics of Deformed Porous Structures

Experimental and computational methods of studying the stress state in the plastic region are characterized by various methods and accuracy of measurements, methods of mathematical processing of experimental information, and interpretation of results. The experimentally determined kinematics as a starting point is the most widely used method to study the stress-strain state in the plastic region. When studying the process of plastic deformation of porous blanks, the model of a rigid-plastic isotropic-strengthening porous body with a loading surface that has the shape of an ellipsoid with semi-axes. It depends on the amount of porosity and the ratio of the associated flow law as a mechanical model of the material. In the axisymmetric extrusion of porous blanks, the viscoplasticity method was used to determine the field of flow velocities based on the results of experimental studies. R-functions were applied to approximate experimentally obtained values. The problem of finding approximations was formulated in a variational statement. Cubic splines of one argument were used to interpolate functions. As a result, an approach was proposed, which consists of a particular sequence of calculating the derivatives of the coordinates of the nodes in time in combination with the R-functions approach. All the calculations were performed in Euler variables, eliminating the need to switch from Lagrangian variables and simplifying the solution. Additionally, this method allowed for working with an irregular and non-rectangular grid in areas with any shape of boundaries. This approach is more effective from the point of view of the approximation’s accuracy and the speed of calculations. Finally, the equation for calculating the porosity in the volume of the deformable workpiece based on the information about the distortion of the dividing grid elements was obtained. For stationary axisymmetric processes, a technique was developed that allowed for replacing the calculation of the accumulated deformation of the base material along the deformation trajectory by integration over the region. A technique was developed for determining the stress-strain state at unstable and stable stages of axisymmetric plastic deformation of porous blanks. The calculation results were compared based on the proposed experimental and calculation techniques and the finite element method.

Perfect plasticity versus damage: an unstable interaction between irreversibility and Γ-convergence through variational evolutions

This paper addresses the question of the interplay between relaxation and irreversibility through quasi-static evolutions in damage mechanics, by inquiring the following question: can the quasistatic evolution of an elastic material undergoing a rate-independent process of plastic deformation be derived as the limit model of a sequence of quasi-static brittle damage evolutions? This question is motivated by the static analysis performed in [J.-F. Babadjian et al. Commun. Pure Appl. Math. 74 (2021) 1803–1854], where the authors have shown how the brittle damage model introduced by Francfort and Marigo (see [G.A. Francfort and J.-J. Marigo, Eur. J. Mech. A Solids 12 (1993) 149–189, G.A. Francfort and J.-J. Marigo, J. Mech. Phys. Solids 46 (1998) 1319–1342]) can lead to a model of Hencky perfect plasticity. Problems of damage mechanics being rather described through evolution processes, it is natural to extend this analysis to quasi-static evolutions, where the inertia is neglected.We consider the case where the medium is subjected to time-dependent boundary conditions, in the one-dimensional setting. The idea is to combine the scaling law considered in [J.-F. Babadjian, et al. Commun. Pure Appl. Math. 74 (2021) 1803–1854] with the quasi-static brittle damage evolution introduced in [G.A. Francfort and A. Garroni, Arch. Rational Mech. Anal. 182 (2006) 125–152] by Francfort and Garroni, and try to understand how the irreversibility of the damage process will be expressed in the limit evolution. Surprisingly, the interplay between relaxation and irreversibility is not stable through time evolutions. Indeed, depending on the choice of the prescribed Dirichlet boundary condition, the effective quasi-static damage evolution obtained may not be of perfect plasticity type.

Research progress and prospects of plastic thermoelectric materials

In recent years, significant progress has been made in the research of plastic thermoelectric materials, for example, Ag<sub>2</sub>S-based alloys. These materials exhibit excellent room-temperature plasticity due to their low slipping barrier energy and high cleavage energy, with synergistic enhancements in plasticity and thermoelectric properties achievable through alloying and doping strategies. The latest study on Mg<sub>3</sub>Bi<sub>2</sub>-based single crystals demonstrated superior performance in terms of plastic deformation capability and room-temperature thermoelectric properties. Microstructural characterization and theoretical calculation have revealed the crucial role of dislocation glide in the plastic deformation process of Mg<sub>3</sub>Bi<sub>2</sub> single crystals, especially, the low slipping barrier energy observed in multiple slip systems. Importantly, the Te-doped single-crystalline Mg<sub>3</sub>Bi<sub>2</sub> shows a power factor of ~55 μW cm<sup>–1</sup> K<sup>–2</sup> and <i>ZT</i> of ~0.65 at room temperature along the <i>ab</i> plane, which exceed those of the existing ductile thermoelectric materials. These findings not only deepen the understanding of microscopic deformation mechanisms in plastic thermoelectric materials but also establish an important foundation for optimizing material properties and developing novel flexible thermoelectric devices. Future applications of these materials in practical devices still face challenges in thermal stability, chemical stability, and interfacial contact. Addressing these issues will promote the application of plastic thermoelectric materials in the field of flexible electronics.

High‐Pressure Torsion: A Simulation Approach for Additive Friction Stir Deposition Processes

The technology of manufacturing aluminum alloy workpieces using additive friction stir deposition (AFS‐D) has been thoroughly investigated. The ambiguous influence of deformation processing modes on the material density was found. Examination of the microstructure in the central zone of the specimens reveals the absence of microdefects typically associated with workpieces obtained through casting or powder metallurgy methods. It has been observed that the distribution of microhardness is significantly affected by the direction of specimen construction, with approximately a 20% difference in values between the periphery and the central part of the specimen. Specimens produced using the AFS‐D method exhibit a homogeneous microstructure characteristic of deformable aluminum alloys. Notably, a uniform distribution of intermetallides on the specimen surface has been identified. This outcome is likely a result of the alloy undergoing recrystallization during the severe plastic deformation process, leading to the formation of an ultradisperse structure. It is important to emphasize that the selection of technological parameters for AFS‐D should consider not only the magnitude of pressure and deformation but also the deformation speed.