CoCrFeNiMn High Entropy Alloy Research Articles

Microstructure evolution, wear and corrosion behavior of WC reinforced CoCrFeNiMn high-entropy alloy composite coatings by induction cladding

In this study, CoCrFeNiMn high entropy alloy (HEA) composite coatings reinforced with different WC particle contents were prepared by induction cladding technology for the first time. The effects of WC particle contents (0–70 wt%) on the microstructure, hardness, wear resistance and corrosion resistance of the coatings were analyzed. The results showed that the coatings prepared by induction cladding exhibited good metallurgical bonding with the substrate. The addition of WC particles led to grain refinement in the CoCrFeNiMn HEA together with second-phase strengthening and solid solution strengthening, improving the microhardness of the coatings. Compared to the average hardness value of 183 HV0.5 for the CoCrFeNiMn HEA coating, the composite coating with 60 wt% WC particle content exhibited the highest average hardness value of 679 HV0.5. The addition of WC particles significantly enhanced the wear resistance of the composite coating, with wear mechanisms including adhesive wear, abrasive wear, fatigue wear and oxidation wear. The composite coating with 60 wt% WC particle content demonstrated outstanding wear resistance, with a specific wear rate value of 0.491 × 10−6 mm3N−1 m−1, representing a reduction of approximately 670 times compared to the CoCrFeNiMn HEA coating. However, the addition of WC particles caused uneven potential distribution within the composite coatings, leading to galvanic corrosion. The WC particles and precipitated carbides increased the defects in the passive film, thus reducing the corrosion resistance of the composite coatings.

Deformation mechanism and microstructure evolution during superplastic deformation of friction stir processed CoCrFeNiMn high entropy alloy

Since superplastic formation offers a significant advantage in preparing the complex structure parts of HEAs, the study of their superplastic behavior is extremely important. Using friction stir processing (FSP) with an improved convex hemispherical shape tool, this study reported for the first time an equiaxed ultrafine-grained CoCrFeNiMn HEA (489 nm) with a maximum elongation of 870% at 675 °C and 3 × 10−4 s−1. This superplastic property is much larger than ever reported in the CoCrFeNiMn HEA, which is even larger than that of the nano-sized CoCrFeNiMn HEA (10 nm) prepared by the high-pressure torsion. A high proportion of high angle grain boundaries and twin boundaries, a hard Cr-rich phase, and the sluggish diffusion effect of the CoCrFeNiMn HEA were primarily responsible for the exceptional superplasticity. Additionally, this study provides the first elucidation of the mechanism underlying Cr precipitation and Cr-rich phase growth, as well as the function of low-energy annealed twins during superplastic deformation. The diffusion of Cr along dislocations and grain boundaries facilitated grain boundary sliding as the predominant deformation mechanism. This study elucidates the superplastic deformation mechanism and microstructure evolution, thereby furnishing theoretical guidance for the practical implementation of superplastic forming of complex components of HEAs. Additionally, it presents an efficient method for fabricating such components.

The Effect of Heat Treatment on the Microstructure and Mechanical Properties of Plasma-Cladded CoCrFeNiMn Coatings on Compacted Graphite Iron

CoCrFeNiMn high-entropy alloy coatings were deposited on compacted graphite iron (CGI) by plasma transfer arc cladding to strengthen and improve the wear resistance (performance) of the surface. The effects of different heat treatment processes on the microstructure and mechanical properties of the CoCrFeNiMn coatings were investigated. Compared with the deposited coating, the single FCC phase in the heat-treated coatings was retained, the grain size of the columnar dendrites decreased, the spacing between the dendrites increased, and the Cr-rich precipitated phase in the grain boundary increased. The heat treatment process had a positive influence on the microhardness and wear resistance of the coatings. The microhardness of the coatings increased after heat treatment. After heat treatment at 660 °C for 90 min, the coating had the highest microhardness of 563 ± 6.9 HV0.2, and it had the best wear resistance.

Superior strength and ductility in a C-containing CoCrFeNiMn high-entropy alloy with heterogeneous microstructure

The present study is focused on the beneficial effects of adding few amounts of carbon (0.76 at. %) and adopting microstructure engineering by a simple thermomechanical treatment to form a heterogeneous microstructure in a CoCrFeNiMn high-entropy alloy. The results demonstrate that the addition of carbon results in significantly higher strength and improved thermal stability when compared to carbon-free alloy under identical conditions. In fact, the addition of carbon results in strengthening through the solute drag effect and solid solution strengthening. Thermodynamic predictions and XRD patterns indicate that carbon addition enhances the tendency of carbide precipitation in the alloy instead of forming an undesirable σ phase. The microstructural observation reveals that the deformed microstructure remains nearly stable during annealing at temperatures up to 750 °C and complete recrystallization occurs after annealing at 1000 °C, resulting in the formation of a fine-grained microstructure. Post-deformation annealing at 800 and 900 °C leads to the formation of heterogeneous microstructures comprising regions with high dislocation density grains alongside recrystallized fine-grained areas. The results suggest a superior synergy between strength and ductility in the annealed sample at 800 and 900 °C, exhibiting the ultimate-tensile strength of ∼1000 and ∼835 MPa. Additionally, these samples demonstrate decent uniform elongation values of ∼10 and 20%, respectively.

Parameters optimization for laser-cladding CoCrFeNiMn high-entropy alloy layer based on GRNN and NSGA-II

In order to improve the bonding strength of FeCoCrNiMn cladding layer, laser power, scanning speed and powder feeding rate were selected as the optimization variables; the aspect ratio, dilution rate and heat affected zone depth of the cladding layer were selected as the optimization indicators; a three-factor three-level full-factor experiment was designed; a nonlinear model of cladding parameters and cladding performance was established by generalized regression neural network algorithm (GRNN), while the error of prediction value and experimental results was less than 10%. A set of optimal Pareto frontiers were obtained by the Non-Dominance Ordering Genetic Algorithm (NSGA-II), and the optimal individuals were obtained based on the equal weights, and the optimal cladding parameters were as follows: laser power 2.33 kW, scanning speed 2.90 m/min, and powder feeding rate 12.46 g/min. The cladding layer prepared under the optimal parameters has a dense cross-section with no defects such as cracks and porosity. The joint optimization using the GRNN neural network and the NSGA-II genetic algorithm can obtain excellent results, and the relative error between the experimental and predicted values can be controlled within 10%. The application of optimized laser process parameters can significantly improve defects such as poor adhesion, cracks and porosity on the surface of the cladding layer, and also improve the surface hardness and wear resistance. The experimental results show that the wear rate of the cladding layer prepared by the optimized parameters is 3.21×10−5 mm3/N·m, which is 1.5 times higher than that of the cladding layer prepared by P=2.1 kW, V=3 m/min and C=9 g/min. The wear mechanism mainly includes abrasive wear, plastic deformation and oxidative wear.

Diffusion in ultra-fine-grained CoCrFeNiMn high entropy alloy processed by equal-channel angular pressing

Grain boundary diffusion in severely plastically deformed (SPD) CoCrFeMnNi high entropy alloy (HEA) has been studied by applying the tracer diffusion technique. After two passes of equal channel angular pressing (ECAP), three untra-fast diffusion paths in ECAP-processed CoCrFeMnNi HEA were distinguished, which were identified with twin boundaries, high-angle grain boundaries and porosity defects. The enhanced diffusivity is induced by a high strain localization in the vicinity of interfaces in a deformation-induced non-equilibrium state that is correlated with the pronounced deformation twinning due to the low stacking fault energy of the material.

Wear-induced microstructural evolution in CoCrNi-based high-entropy alloys at cryogenic temperature

Elucidating the tribological behaviors of CoCrNi-based high-entropy alloys (HEAs) at cryogenic temperatures is crucial for their practical application. This work uncovers the correlation between the wear-induced microstructural evolutions and tribological properties of single-phase CoCrFeNiMn HEA and heterogeneous CoCrFeNiAl HEA upon two contact conditions at 173 K. When CoCrFeNiMn HEA matches with GCr15 rather than Si3N4, low contact stress and high flash temperature suppress the inhomogeneous deformation initiated by martensitic transformation and in turn create a gradient nanograined tribo-layer activated by high-density dislocations and nano-scale deformation twins, which progressively accommodates the frictional strain and reduces wear by an order of magnitude. Instead, the tribological properties of the CoCrFeNiAl HEA sliding against Si3N4 are slightly superior to those sliding against GCr15, owing to the elevated contact stress and reduced flash temperature thicken the protective recrystallized nanocrystalline tribo-layer. Our findings offer guidance for optimizing the tribological properties of HEAs in cryogenic environments.

Effects of current density on the mechanical properties and microstructures of CoCrFeNiMn high-entropy alloy

Electrically assisted forming has been a reliable method for enhancing the formability of metal components for decades. This study investigates the mechanical properties and microstructures of an equiatomic CoCrFeNiMn high-entropy alloy (HEA) under electrically assisted tensile (EAT). The results indicate that the CoCrFeNiMn HEA exhibits lower flow stress and elongation under EAT compared to samples deformed at room temperature (RT). The sample's temperature increases with current density, and the primary factor influencing the HEA's mechanical properties during EAT is the Joule heating effect. A model about yield strength (YS) increment is established to predict the YS of the HEA under EAT at different temperatures. As the amount of Joule heating rises, the dislocation width increases, reducing the lattice friction stress and resulting in an exponential decay of YS. Increased Joule heating caused by current leads to a higher dynamic recovery rate, resulting in a reduced proliferation rate of geometrically necessary dislocations. However, the change in dislocation recovery coefficients is little affected by the current density in CoCrFeNiMn HEA when the dynamic recovery produced by the current is not sufficient to increase the fracture strain. Deformation twins (DTs) form during deformation at RT and 10 A/mm2. However, as the current density surpasses 20 A/mm2, the flow stress becomes insufficient to induce the formation of DTs, leading to a decrease in strain-hardening ability and elongation. This study provides an experimental and theoretical foundation for forming HEA components.

Steam oxidation properties of graphene reinforced bioinspired laminated CoCrFeNiMn high-entropy alloy matrix composites at 1000 ℃

Laminated CoCrFeNiMn high-entropy alloy (HEA) matrix composites reinforced with 1.0 wt% graphene nanoplatelets (GNPs) were fabricated by mechanical ball milling and flake powder metallurgy, and were isothermal oxidized at 1000 ℃ for 100 h. Vacuum hot-pressure sintering (VHPS) shows a distinct nacre structure with the microstructure composed of FCC matrix phase, Cr23C6, CrMn1.5O4 precipitated phases, numerous dislocations and twins. High-temperature oxidation tests showed that the composites had mass gains at 12 h intervals from 12 to 100 h respectively. The oxidation kinetic curve changes from a linear pattern in the early stages to an exponential pattern in the later stages, which demonstrates better long-term oxidation resistance. The anisotropy of the laminated structure results in excellent resistance to high-temperature steam oxidation in the vertical lamellar direction. Observation of the cross-section reveals that although Cr2O3 (inner layer) is present, (Mn, Cr)3O4 and Mn3O4 are the dominant oxides (outer layer). Elemental depletion zones for Mn and Cr exist in the region of the matrix near the oxide scales. The results show that the oxidation resistance of the laminated GNPs/CoCrFeNiMn composites is mainly influenced by the diffusion of Mn and Cr elements, the microstructure of the laminations and the internal oxidation.

Preparation of graphene film reinforced CoCrFeNiMn high-entropy alloy matrix composites with strength-plasticity synergy via flake powder metallurgy method

Inspired by the design principle of pearl structure, a bottom-up flake powder self-assembly arrangement strategy, flake powder metallurgy, is used to prepare graphene films (GFs) reinforced CoCrFeNiMn high-entropy alloy (HEA) matrix composites with a pearl laminated structure. Flaky HEA powder was prepared by ball milling method and homogeneously mixed with Ni plated GFs. Vacuum hot-press sintering (VHPS) technique was carried out to solidify the mixed powders to obtain composites with uniform distribution of GFs(Ni) and flaky HEA. The results show that the bottom-up preparation strategy can effectively fabricate bionic laminated HEA matrix composites, and the composites have a distinct pearly laminated structure. The tensile strength of the composites with 5 vol% GFs(Ni) content reached 834.04 MPa, and the elongation reached 26.58 %. The compressive strength in parallel and perpendicular laminar directions reached 2069.66 MPa and 2418.45 MPa at 50 % strain, respectively. The laminated GFs(Ni)/HEA matrix composites possessed excellent strength and maintained good plasticity. In this study, the strengthening and toughening mechanism of the laminated GFs(Ni)/HEA matrix composites is discussed in detail, and the results show that the laminated structure and GFs(Ni) are favorable for the hardening and strengthening of the HEA matrix.

The Microstructure and Mechanical Properties of High Entropy Alloy CoCrFeNiMn Matrix with Cr3C2 Reinforcement and Ag, BaF2/CaF2 Solid Lubrication

A series of CoCrFeNiMn high-entropy alloy matrix self-lubricating composites were prepared by spark plasma sintering. The composites are composed of an FCC phase, Cr7C3, Ag, and eutectic fluoride BaF2/CaF2 phases. The microstructure of the composites is uniform. The additional phases distribute along the boundary of equiaxed grains of the FCC phase. The compressive yield strength and fracture toughness decrease with the increase of eutectic fluoride BaF2/CaF2. The composites are susceptible to brittle cleavage fracture.

Design and development of porous CoCrFeNiMn high entropy alloy (Cantor alloy) with outstanding electrochemical properties

CoCrFeNiMn high entropy alloys are among the most well-studied high entropy alloys that exhibit reasonable strength and outstanding ductility. In the present study, porous CoCrFeNiMn foams have been developed by the addition of copper in the base high entropy alloy by arc melting followed by its removal through an electrochemical dealloying process. Microstructure characterization of the as-cast samples confirmed limited solubility of copper in the matrix while the majority of the copper was found to segregate to interdendritic areas. Removal of copper from the interdendritic areas was successfully carried out by an electrochemical dealloying process which resulted in the development of foams with interconnected porosity. CoCrFeNiMn foams with different levels of porosities were successfully developed by varying the amount of added copper in the base HEA and its removal by a dealloying process. The electrochemical performance of the developed foams was assessed by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). One of the developed foams was found to exhibit an areal capacitance of 1.56 F cm−2 at 2 mA cm−2 which is more than 2x times higher than the value reported for recently developed porous AlCoCrFeNi high entropy foam. Developed foam, besides showing excellent values of areal capacitance, demonstrated capacitance retention of 114.6% after 5000 cycles at 8 mA cm−2. The excellent electrochemical performance of the developed high entropy foams exhibits their potential to be used as electrode materials for supercapacitor applications and was attributed to the insertion of interconnected porosity in the base HEA.

Effects of laser power on microstructures and mechanical properties of CoCrFeNiMn high entropy alloy with the addition of Y2O3 by directed energy deposition

The bulk CoCrFeNiMn high entropy alloy with the addition of Y2O3 is fabricated by directed energy deposition, and its microstructures and mechanical properties were investigated in relation to laser power. The XRD results revealed that FCC and Cr-rich precipitates were constant in all samples, regardless of laser power. Moreover, the lattice constant is maximum at 800 W laser power due to the increased Y content. The EBSD results indicated that higher laser power can coarse grain, but it is refined at 800 W due to the increased concentration of new compounds and Y2O3 in the sample. The texture strength of the sample processed at 1000 W is approximately 1.6 times greater than that observed in the 700 W process. Besides, the sample shows the minimum texture strength at 800 W, owing to the action of small grain size. Additionally, the higher laser power is beneficial to form <001> texture along the scanning direction and the building direction. The laser power has a proportional relationship to the average KAM value and low-angle grain boundary. The results of the deformation behavior suggest that the sample has excellent mechanical properties at 800 W, which exhibits ductile fracture.

Grain size dependent mechanical properties of CoCrFeMnNi high-entropy alloy investigated by shear punch testing

The effect of grain size on the mechanical properties of an equiatomic CoCrFeNiMn high-entropy alloy (HEA) was investigated by shear punch testing (SPT) as a miniature test method and Vickers hardness measurements. A Hall–Petch relationship was developed for the dependency of shear yield stress (SYS) on the average grain size (D). The correlation of the SYS and ultimate shear strength (USS) to the tensile yield stress (TYS) and ultimate tensile strength (UTS) values were also studied. A wide range of grain sizes was obtained by the thermomechanical processing of cold rolling and annealing at hot temperatures, where the primary recrystallization and grain growth phenomena were used for grain refinement and grain coarsening, respectively. Based on the obtained results and literature data, the Hall–Petch relationships of SYS = 88.9 + 301.1/√D and TYS = 167 + 520/√D were proposed, respectively. Moreover, the correlation of tensile test properties with those predicted by the shear punch test was also investigated. Accordingly, the relationships of TYS = 1.76 × SYS and UTS = 1.33 × USS were obtained, where the former is in excellent agreement with the von Mises yield criterion based on the plasticity theory, and the latter is influenced by the work-hardening behavior of the material and dynamic phenomena during plastic deformation.

Insights into the microstructural evolution and wear behavior of underwater friction stir processed CoCrFeNiMn high-entropy alloy

The equiatomic CoCrFeNiMn high-entropy alloy (HEA) has demonstrated excellent strength-ductility-toughness synergy over a wide range of temperatures, especially at cryogenic temperatures, but poor wear resistance. Herein, we explored the feasibility of constructing ultrafine-grained (UFG) surface layer on the CoCrFeNiMn HEA by underwater friction stir processing (FSP) and evaluated its dry sliding wear behavior. During air-FSP of CoCrFeNiMn HEA, continuous and discontinuous dynamic recrystallization (CDRX and DDRX) compete with each other responsible for grain refinement. Water-FSP promotes the occurrence of DDRX and inhibits the growth of recrystallized grains, leading to the formation of an UFG surface layer with average grain size of 1.14 ± 0.78 μm. The surface hardness of base material is about 179 HV, which is increased to 216 HV for the air-FSPed sample and 275 HV for the water-FSPed sample. Nonetheless, the three samples exhibit similar wear behavior, mainly adhesive wear and oxidation wear. This is mainly attributed to a combination of the formation of oxides on the worn surfaces during sliding and the significantly reduced strain-hardening effect with decreasing grain size. This work provides a fundamental understanding of the microstructural evolution of CoCrFeNiMn HEA during FSP as well as its sliding wear behavior before and after FSP.

A novel method to examine the effect of Al addition on the microstructure of CoCrFeNiMn high-entropy alloy

A novel approach was employed to investigate the effect of Al addition on the microstructure of a CoCrFeNiMn high-entropy alloy (HEA). A two-layer structure consisting of CoCrFeNiMn with a low-melting Al interlayer was subjected to heat treatment at temperatures of 600, 700, and 800 °C for up to 48 h. The purpose was to directly examine phase formation and phase stability in Al-added alloys. As a result, the heating process at 700 and 800 °C led to the formation of a few microns multilayers, primarily composed of B2-type NiAl and σ phases at the interface and the earlier temperature showed relatively good bonding. These experimental findings were complemented by CALPHAD predictions and considered physical aspects for phase prediction. This concept holds significant benefits for alloy design as it offers a cost-effective and time-saving method to investigate phase formation and stability at different temperatures in complex multi-component alloys.

Структура и свойства композиционного покрытия на основе высокоэнтропийного сплава, упрочненного частицами CrB

Introduction. Currently, a new class of materials, namely high-entropy alloys, is an active area of research. One of the areas of its application is the fabrication of protective coatings with high performance properties. The high-entropy alloy of CoCrFeNiMn composition is characterized by high ductility, which is retained both at elevated and cryogenic temperatures, as well as high thermal stability and, thus, can be considered as promising materials for protective coatings formation. At the same time, its disadvantages are low hardness and strength. It is known that the reinforcement of the CoCrFeNiMn high-entropy alloy with hardening particles is an effective way to improve the mechanical properties of coatings. It is assumed that the addition of hardening boride particles affects positively on the mechanical characteristics of the alloy. The aim of this work is to study the structural and phase states and wear resistance of coatings based on a CoCrFeNiMn high-entropy alloy reinforced with CrB particles. Coatings obtained by the method of non-vacuum electron-beam surfacing of powder mixtures with different mass ratios of CoCrNiMn metal powders to the CrB powder (100:0, 95:5, 90:10, 80:20, 70:30) are studied in this work. To investigate the structure and phase composition of the coatings, such methods as optical microscopy, scanning electron microscopy and X-ray diffraction analysis were applied. To study the elemental composition, energy-dispersive X-ray analysis was used. The mechanical properties were evaluated based on the microhardness measuring results. The wear resistance of the coatings was determined under conditions of dry sliding friction during reciprocating motion. Results and discussion. The addition of CrB powder to the surfacing mixture led to the formation of eutectic structures. When 5 wt. % CrB was added, a hypoeutectic structure is formed in the coating. An increase in the amount of CrB leads to the formation of coatings with a hypereutectic structure containing primary borides. The main phases found in the coatings are the fcc solid solution, and (Cr,Mn,Fe)2B, (Ni,Co,Mn)2B, CrB borides. All the studied coatings are characterized by an adhesive wear mechanism. The addition of 20 % and 30 % CrB to the surfacing mixture composition results in the wear resistance increase of the high-entropy alloy-based coatings by 3.6 and 6.1 times, respectively.

Effect of synergistic cavitation erosion-corrosion on cavitation damage of CoCrFeNiMn high entropy alloy layer by laser cladding

The CoCrFeNiMn high entropy alloy (HEAs) clad layer was prepared on the surface of 304 stainless steel using coaxial powder feeding laser cladding. The effects of laser energy density on the macroscopic residual stress, crystallographic characteristics, microhardness, corrosion resistance and cavitation erosion (CE) resistance of HEAs clad layer were studied. With the decrease of laser energy density from 45 J/mm2 to 36 J/mm2, pore defects and abnormal coarsening of microstructure in HEAs cladding layer can be effectively avoided, the average grain size can be refined to 74.3 ± 1.7 μm, the average Schmidt factor is 0.43, which also shows the highest dynamic passivation tendency and corrosion resistance in artificial seawater. After 10 h-CE, the carrier density ND in the passivation film of HEAs clad layer can be as low as 3.24 ± 0.08 × 1022 cm−3, and the lowest mean depth erosion rates (MDER) is 0.68 ± 0.07 μm/h, which is much lower than that of 304 stainless steel substrate (4.23 ± 0.13 μm/h). The excellent CE resistance of the HEAs clad layer is attributed to the fact that its grains can effectively resist the plastic deformation and the surface passivation film can maintain a relatively high degree of integrity and continuous level after long aging CE, which has a considerable application prospect in marine engineering.

Effects of carbon doping on annealing behavior of a CoCrFeNiMn high-entropy alloy

A 1 at% carbon non-equiatomic doped Co19Cr5Fe38Ni19Mn19 high-entropy alloy was synthesized by vacuum arc-melting in a high-purity argon atmosphere, followed by homogenization, cold rolling, and annealing under various conditions. The evolutions of microstructure and mechanical properties during annealing were systematically studied and compared with the carbon free alloy. Results showed that nano-sized fibrous deformation grains were formed in the 90% cold rolled alloys, resulting in high strength but low plasticity. Recovery sub-structures and recrystallized grains gradually formed with increasing annealing temperature, leading to a significant decrease in defect density, thereby softening the materials and increasing their plasticity. The early stage of recovery was mainly related to the migration of vacancy and interstitial carbon atoms, while dislocation climb became the main recovery mechanism in the late recovery stage. The carbon-doped alloy exhibited a higher recovery activation energy compared with the carbon free alloy. Therefore, 1 at% interstitial carbon effectively increased the recovery and recrystallization resistance of the Co19Cr5Fe38Ni19Mn19 alloy.

Synchrotron High-Energy X-ray &amp; Neutron Diffraction, and Laser-Scanning Confocal Microscopy: &lt;i&gt;In-Situ&lt;/i&gt; Characterization Techniques for Bulk Nanocrystalline Metals

This report is aimed at giving an overview of the significance of the novel and innovative microstructural and microscopic characterization techniques for bulk nanostructured metals processed by severe plastic deformation, specifically high-pressure torsion (HPT). In practice, the microstructural relaxation behavior upon heating of nanostructured 316L stainless steel and CoCrFeNi high-entropy alloy was characterized by in-situ heating neutron diffraction measurements; the heterogeneous phase distribution of an HPT-bonded hetero-nanostructured Al-Mg alloy was examined using synchrotron high-energy X-ray diffraction; and the microstructural evolution upon heating of a nanostructured CoCrFeNiMn high-entropy alloy was examined by laser-scanning confocal microscopy. These novel techniques are complementary to each other and any other in- or ex-situ testing methods, especially when nanocrystalline metals are transforming microstructurally and compositionally with temperature and time in a hierarchical manner. The outcomes of the studies emphasize the importance of the methodologies and the development of characterization techniques for further in-depth exploration in the research field of severe plastic deformation.