High-pressure Torsion Samples Research Articles

Optimizing the mechanical and corrosion properties of an ultrafine-grained Al-Cu-Mg alloy through cyclic deformation: Clusters and lattice defects

To optimize its corrosion and mechanical properties, an Al-Cu-Mg alloy is cyclically processed by high-pressure torsion (HPT), involving a 1/2 turn clockwise and a 1/2 turn counter-clockwise per cycle. The dislocation density increases to 3.04×1014 m−2 on 1 cycle HPT and decreases gradually to 2.23×1014 m−2 for higher cyclic rotations (i.e. 5 cycle HPT). Due to the rapid elimination of the geometrically necessary dislocations, the refinement of grain size in cyclic HPT is more efficient than the monotonic HPT (i.e. it decreases from 2.48 μm to 112 nm on 1 cycle HPT). The HPT samples are electrochemically corroded in a simulated seawater environment. 1-cycle HPT process causes a strong increase in hardness (to 232 HV) and an increase in corrosion potential (to −0.517 V). The trade-off between hardness/strength and corrosion resistance is broken on cyclic HPT processing. Aided by excess vacancies induced by HPT, Cu-Mg clusters form on and near grain boundaries through a ‘vacancy-pump’ mechanism, causing solute depleted zones (SDZ) adjacent to GBs. The combined effects of ultrafine grains, solute cluster segregation and SDZs enhance the strength and corrosion resistance of the Al-Cu-Mg alloys. This study provides a potential strategy to design the microstructures of an Al alloy, and to achieve a higher hardness and a better corrosion performance of that material.

Effect of intermediate processing treatment on the structure and mechanical properties of Al–4 wt%Cu–3 wt%Mn alloy manufactured by electromagnetic casting followed by high-pressure torsion (HPT)

In this work, a thermally stable model Al–4Cu–3Mn (wt%) alloy has been manufactured by electromagnetic casting (EMC), followed by compression, intermediate heat treatment and high-pressure torsion (HPT). Structural changes of the alloy during subsequent processing stages have been analysed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and the X-ray diffraction (XRD). The results indicate that variations in the intermediate heat treatment temperature of the compressed samples lead to a significant difference in strain hardening and thermal stability after HPT. According to microstructure investigations the hardening of samples processed by HPT resulted from formation of mixture of grains and subgrains with high dislocation density as well as mechanical fragmentation of eutectic Al2Cu particles and precipitation of nanoscale Mn-rich dispersoids which are identified as Al6Mn. The intermediate heat treatment of the EMC rod at 350 ºC for 3 hours and heat treatment of HPT sample at 250 ºC for 5 hours exhibited the best mechanical properties in terms of ultimate tensile strength (UTS), yield strength (YS) and elongation (El), reaching 610 MPa, 560 MPa and 10 % respectively. At the same time intermediate annealing at 450 °C makes the HPT processing ineffective.

Degradable Zn–5Ce alloys with high strength, suitable degradability, good cytocompatibility, and osteogenic differentiation fabricated via hot-rolling, hot-extrusion, and high-pressure torsion for potential load-bearing bone-implant application

Zinc (Zn)-based alloys are considered the next-generation biodegradable material for promising bone-implant devices due to their good degradability, formability, and functionality. Nevertheless, the as-cast Zn alloys showed a low strength-toughness, making it challenging to meet the mechanical properties requirements for high-load-bearing bone implants due to their hexagonal close-packed structure, coarse grain size, and less sliding system. Herein, we have developed biodegradable Zn–5Ce alloys by cerium (Ce) alloying followed by hot-rolling, hot-extrusion, and high-pressure torsion (HPT), respectively, for potential bone-implant application. Mechanical testing revealed that the HPT sample exhibited the best mechanical performance matching among the Zn–5Ce samples with a high ultimate tensile strength of ∼345 MPa, yield strength of ∼230 MPa, a moderate elongation of ∼11.4%, and macro-hardness of ∼96.6 HB. Electrochemical corrosion and static immersion testing revealed that the HPT sample showed the highest electrochemical corrosion rate of ∼416 μm/y and degradation rate of ∼43.8 μm/y in Hanks' solution among the Zn–5Ce samples, which is suitable for degradation rate requirements for bone-implant application. Bio-tribological testing revealed that the HPT sample showed high bio-tribological properties matching in Hanks’ solution with the lowest friction coefficients of ∼0.530 and moderate wear loss of ∼2.2 mg. Cytocompatibility and osteogenic differentiation assessment revealed that the diluted extract of the HPT sample showed the highest cytocompatibility towards 3T3 and MG-63 cells and osteogenic differentiation performance towards 3T3 cells among the most diluted extracts. Accordingly, the HPT Zn–5Ce sample is expected to be used for high-load-bearing degradable bone-implant devices, including bone fixation and guided bone regeneration systems.

Micro-mechanisms of deformation and strengthening during high pressure torsion of CoCuFeMnNi high entropy alloy

The equiatomic FCC CoCuFeMnNi HEA subjected to high pressure torsion (HPT) till 5 turns, showed a fourfold increase in hardness and three orders of magnitude decrease in grain size with an insignificant change in strain rate sensitivity and activation volume. There is a gradual transition from planar slip at low strain to twinning followed by shear banding at high strain accompanied by conversion of low angle to high angle grain boundaries, resulting in average grain size of 55 ± 33 nm at the periphery of 5 turn HPT sample. Atom probe tomography revealed that nano-clusters present in FCC matrix in the homogenized sample underwent partial dissolution during HPT to increase the copper concentration from 8.24 ± 3.29 to 17.02 ± 1.51 atomic%, contributing to significant solid solution strengthening in addition to dislocation and grain size strengthening, leading to tremendous increase in hardness (539 to 1941 MPa). Transient instrumented micro and nano-indentation tests yield activation volume between 12 and 17 b3 for the homogenized and HPT processed samples with three orders of magnitude difference in grain size and dislocation density. This indicates that the dislocation–solute environment interaction is the rate controlling mechanism during the deformation of the investigated HEA. The present work provides a unique pathway to design high entropy alloys that can explore and utilize non-equilibrium solid solution strengthening as a major strengthening mechanism to achieve high strength.

Effect of high-pressure torsion on high cycle fatigue of commercially pure Cu: Some insights from formation of surface micro-cracks

In most technical applications, fatigue is related to highly localized load distributions. While high-pressure torsion (HPT) materials cannot prevent crack initiation, they promise to improve the resistance to crack nucleation and propagation. Herein, commercially pure Cu was processed through HPT at a pressure of 6 GPa up to 50 turns. Small “cantilever” type samples were fabricated from annealed and HPT samples. The cantilever samples were subjected to fully-reversed cyclic bending. The maximum stress amplitude was chosen to reach the high cycle fatigue regime, and the experiments were stopped when the resonant frequency decayed by 20%. Compared to the annealed samples, the HPT samples showed higher lifetimes. The grain size in the HPT samples remained stable during fatigue, and dislocation substructures, a stacking of parallel dislocations, could be observed in all samples. In HPT samples, the area fraction of surface micro-cracks increased with the local stress amplitude. This can be attributed to the inhibition of crack nucleation at low stresses due to the high strength of HPT samples and the crack arrest at the boundaries of their ultra-fine grains. The obtained insights into the microstructure-fatigue response relationship are vital for understanding the initial stages of fatigue failure in ultra-fine-grained materials and their technological adoption for applications in extreme environments.

Распределение микротвердости по поверхности металлического стекла на основе циркония, подвергнутого интенсивной пластической деформации кручением

Identifying the peculiarities of the transformation of the structure and properties of bulk metallic glass (BMG) under high-pressure torsion (HPT) is of great interest. It is known that under HPT, the degree of deformation differs from the center to the edge of a disk which leads to the non-uniformity of the structure of obtained specimens. The change in microhardness value indicates the direction of change in BMG structure under the HPT, and the microhardness distribution indicates the HPT-specimen non-uniformity. The aim of the study is to identify the HPT influence on the microhardness value and microhardness distribution over the surface of specimens of amorphous alloys using an example of Vit105Zr-based BMG (Zr52.5Cu17.9Ni14.6Al10Ti5). The authors studied the distribution of microhardness over the surface of Vit105 Zr-based bulk metallic glass (BMG) in the initial state, in the state after HPT at n=1 and n=5 rotations, and after relaxing annealing. The study shows that the initial Vit105 BMG is characterized by a small spread in microhardness values, which indicates the material's high homogeneity. By reducing the excessive free volume, relaxing annealing increases microhardness without a significant increase in the spread of its values. HPT leads to a decrease in the zirconium BMG microhardness, which indicates an increase in the excessive free volume, but, at the same time, increases the uneven microhardness distribution over the specimen, while the microhardness values in one half of the HPT sample (n=1) are higher than in the other one. It demonstrates that BMG specimen deformation during HPT is related to the specific loading mechanisms.

Phase Composition, Nanohardness and Young’s Modulus in Ti-Fe Alloys after Heat Treatment and High Pressure Torsion

Four titanium-iron binary alloys were studied. They were preliminarily annealed in the (α + β) and (α + TiFe) regions of the Ti-Fe phase diagram. The changes in the phase composition, nanohardness, and Young’s modulus of the annealed alloys before and after high pressure torsion (HPT) were investigated. Alloys with high iron content after HPT contain a large fraction of the ω phase. The nanohardness of the material in the middle of the radius of the HPT samples varies in the same range of values between 4.4 and 5.8 GPa, regardless of the preliminary annealing. Young’s modulus is a parameter sensitive to structural and phase changes in the material. After HPT, it increases by a factor of 1.5 after preliminary annealing in the (α + β) region in comparison with that in (α + TiFe) region.

Influence of high pressure torsion on microstructure evolution and mechanical properties of AZ80/SiC magnesium matrix composites

The effect of applying 1, 5 and 10 turns of high pressure torsion (HPT) as a severe plastic deformation technique on the microstructural evolution, hardness, tensile and shear strength of an as-cast AZ80-SiC magnesium matrix composite is investigated in the present study. The results show that HPT at room temperature refines the microstructure of the as-cast material having an average grain size of 176 ± 58.9 μm to a fine grain structure with average grain sizes of 4.2 ± 4.1 μm and 2.5 ± 2.1 μm in 5 and 10 turns HPT samples, respectively. In addition, ultra-fine grained regions (grain size <1 μm) with volume fractions of about 12, 27 and 31 vol% are obtained in the samples processed by 1, 5 and 10 turns of HPT, respectively. Based on microstructural observations, it is concluded that 5 and 10 turns HPT samples are almost similar in terms of grain size, recrystallized fraction, low-angle grain boundary fraction, and recovered parts. The ultimate tensile and shear (achieved from shear punch tests) strengths of the as-cast sample are improved by applying HPT due to grain size and texture hardening mechanisms. The highest strength values are obtained after performing the first HPT turn due to the more significant effect of texture hardening in comparison to the 5 and 10 turns HPT-processed samples. Similar to the strength results, the hardness of the as-cast material is also enhanced from 66 ± 6 HV to about 123 ± 3 HV through HPT processing.

Multiscale Modeling of the Strength and Ductility Paradox for High-Pressure Torsion Samples With Gradient Microstructure

Abstract Severely plastically deformed microstructures of pure copper were produced by subjecting cylindrical copper samples to high-pressure torsion. The effects of this procedure on introducing gradient microstructure and subsequent mechanical behavior were investigated by utilizing electron backscatter diffraction and performing Vickers hardness/tensile testing. A crystal plasticity-continuum dislocation dynamics modeling effort was performed to predict the mechanical performance of these samples. The model includes mechanisms based on the gradient of dislocation density and grain size, back stress fields of grain boundaries, dislocation density transmission across grain boundaries, and stress/strain gradient effects.

Properties of HPT-Processed Large Bulks of p-Type Skutterudite DD0.7Fe3CoSb12 with ZT &gt; 1.3

The influence of shear strain on the microstructural, physical, and mechanical properties was studied on large bulk samples (diameter: 30 mm, thickness: 1 or 8 mm), which were consolidated by high-pressure torsion (HPT) from a commercial powder DD0.7Fe3CoSb12. Particularly, the thick sample (mass �53 g) allowed measuring the thermoelectric (TE) properties with respect to various orientations of the specimen in the sample. All data were compared with those of a hot-pressed (HP) reference sample, prepared with the same powder. Transmission electron microscopy, as well as X-ray powder diffraction profile analyses, Hall measurements, and positron annihilation spectroscopy, supported these investigations. Furthermore, synchrotron data for the temperature range from 300 to 825 K were used to evaluate the changes in the grain size and dislocation density as well as the thermal expansion coefficient via the change in the lattice parameter during heating. In addition, hardness and direct thermal expansion measurements of the HPT samples were performed and compared with the HP reference sample's values. With the increase of the shear strain from the center to the rim of the sample, the electrical resistivity becomes higher, whereas the thermal conductivity becomes lower, but the Seebeck coefficient remained almost unchanged. For the thin as well as thick samples, the enhanced electrical resistivity was balanced out by a decreased thermal conductivity such that the maximum ZT values (ZT = 1.3-1.35 at 856 K) do not vary much as a function of the shear strain throughout the sample, however, all ZTs are higher than that of the HP sample. The thermal-electric conversion efficiencies are in the range of 14-15 (for 423-823 K). With similar high ZT values for the n-type skutterudites, fabricated in the same fast and sustainable way, these p- and n-type skutterudites may serve as legs for TE generators, directly cut from the big HPT bulks. ©

Local hydrogen accumulation after cold forming and heat treatment in punched advanced high strength steel sheets

Hydrogen embrittlement is one of the most crucial problems in the application of advanced high strength steel (AHSS) sheets for the automotive industry. Especially, the severe plastic deformation in punched edges makes the components susceptible to hydrogen assisted cracking (HAC). While small amounts of hydrogen are measured in the bulk material, hydrogen concentration increases in the micrometer-sized shear affected zone many times, along with severe plastic deformation. To contribute to the understanding of local microstructure and local stress states on the hydrogen accumulation in the shear affected zone, two industrial AHSS were investigated. Both steels had the same ultimate tensile strength of 1200 MPa, but different uniform elongations. High-pressure torsion (HPT) deformed samples were used to represent the material state in the shear affected zone. Thermal desorption spectroscopy (TDS), X-ray diffraction (XRD), magnetic retained austenite measurements and electron backscattering diffraction (EBSD) in a high resolution secondary electron microscopy (SEM) were applied among other techniques to gain more insights with microstructural resolution. The hydrogen analysis results of the HPT samples were correlated with the local hydrogen trapping capacity in punched edges. Finally, a simplified “two-zone” model considering the bulk and punched edge as separate zones was developed in order to estimate the local hydrogen concentration of punched AHSS sheets as a function of hydrogen bulk concentration. In a concluding remark it is shown, that the effect of the hydrostatic stress field as trap site is negligibly small compared to other traps.

Evolution of microstructure and hardness during artificial aging of an ultrafine-grained Al-Zn-Mg-Zr alloy processed by high pressure torsion

An ultrafine-grained (UFG) Al-4.8%Zn-1.2%Mg-0.14%Zr (wt%) alloy was processed by high pressure torsion (HPT) technique and then aged at 120 and 170 °C for 2 h. The changes in the microstructure due to this artificial aging were studied by X-ray diffraction and transmission electron microscopy. It was found that the HPT-processed alloy has a small grain size of about 200 nm and a high dislocation density of about 8 × 1014 m−2. The majority of precipitates after HPT are Guinier–Preston (GP) zones with a size of ~ 2 nm, and only a few large particles were formed at the grain boundaries. Annealing at 120 and 170 °C for 2 h resulted in the formation of stable MgZn2 precipitates from a part of the GP zones. It was found that for the higher temperature the fraction of the MgZn2 phase was larger and the dislocation density in the Al matrix was lower. The changes in the precipitates and the dislocation density due to aging were correlated to the hardness evolution. It was found that the majority of hardness reduction during aging was caused by the annihilation of dislocations and some grain growth at 170 °C. The aging effect on the microstructure and the hardness of the HPT-processed specimen was compared to that observed for the UFG sample processed by equal-channel angular pressing. It was revealed that in the HPT sample less secondary phase particles formed in the grain boundaries, and the higher amount of precipitates in the grain interiors resulted in a higher hardness even after aging.

Resistivity and Thermal Expansion (4.2–820 K) of Skutterudites after Severe Plastic Deformation via HPT

Thermoelectric materials with a high figure of merit, ZT, are the essential basis to build thermoelectric generators, which can directly convert heat into electricity. Severe plastic deformation (SPD) via high‐pressure torsion (HPT) was successfully applied to enhance ZT of ball‐milled and hot‐pressed skutterudites as well as to produce bulk nanostructured skutterudites directly from powders. SPD introduces many defects into the sample and in parallel the crystallite size is significantly reduced. During measurement‐induced heating these defects anneal partially out, and the grains grow. In this work for the first time systematically the changes of the temperature‐dependent electrical resistivity and of thermal expansion were compared. It could be shown that for p‐ and n‐type skutterudites, being hot‐pressed and HPT‐processed as well as directly HPT‐processed from compacted powder, these changes occur more or less simultaneously within the same temperature ranges. This evaluation gives a much deeper insight into the thermoelectric behavior of HPT samples under the influence of changing temperature.

A critical evaluation of microstructure-texture-mechanical behavior heterogeneity in high pressure torsion processed CoCuFeMnNi high entropy alloy

The present study aims to understand the evolution of textural and microstructural heterogeneity and its effect on evolution of mechanical properties of an equiatomic FCC CoCuFeMnNi high entropy alloy (HEA) disc subjected to high pressure torsion (HPT). HPT was performed on disc specimen with a hydrostatic pressure of 5 GPa for 0.1, 0.5, 1 and 5 turns at room temperature where the hardness saturated at 1941 MPa at the periphery of the sample after five turns. Synchrotron diffraction texture analysis of five-turn HPT sample reveals characteristic shear texture with the dominance of A {11⇀1⇀}<110> and A* {11⇀1⇀}<112> components near central region of the disc and it shifts to C {001}<110> component near the periphery of the disc. X-ray diffraction analysis shows decrease in crystalline size with simultaneous increase in dislocation density for five-turn HPT sample with increasing strain from centre to the periphery of the disc. Microstructural analysis using electron back scatter diffraction and transmission electron microscopy indicates extensive grain fragmentation (≈55 nm) at the periphery of five-turn sample. The evolution of hardness from centre to the periphery of the disc cannot be explained only on the basis of evolution of grain size and dislocation density. The increase in contribution from solid solution strengthening due to partial dissolution of copper rich nano-clusters is expected to be the underlying cause for increase in the hardness. Thus, evolution of gradient microstructure, texture, and chemistry opens up new vistas for designing functionally graded materials for engineering applications.

Processing and characterization of a multibeam sputtered nanocrystalline CoCrFeNi high-entropy alloy film

Physical vapor deposition (PVD) is a well-known route for manufacturing hard coatings. In recent years, PVD has also been applied to create high-entropy alloy (HEA) thin films. HEAs are multicomponent alloys with nearly equal atomic fractions. To achieve the desired composition, typically alloy targets are used in the deposition process. The present work demonstrates that HEA thin films can also be processed using a multiple beam sputtering system in PVD, which does not require preliminary manufacturing of HEA targets, but rather uses commercially pure metal targets. The effectivity of this technique was demonstrated on a nanocrystalline CoCrNiFe HEA film with a thickness of about 1 μm. A part of the compositional gradient sample exhibited equal elemental fractions. The microstructure and the hardness of this part of the PVD film were studied in detail, and the results were compared with those obtained on a bulk nanocrystalline sample having the same chemical composition, but was prepared by the high pressure torsion (HPT) technique. The crystallite size and the texture were characterized by X-ray diffraction, while the hardness was measured by nanoindentation. The PVD film exhibited an exceptionally high hardness of 9.8 ± 0.3 GPa, a value that was notably higher than that determined for the HPT sample (7.3 ± 0.3 GPa). This study also demonstrated the capability of this new multiple beam sputtering technique for the production of compositional gradient samples with a wide range of elemental concentrations, enabling combinatorial analysis of multiple elements high-entropy alloy.

Effect of mechanically induced structural rejuvenation on the deformation behaviour of CuZr based bulk metallic glass

Severe plastic deformation of bulk metallic glasses leads to rejuvenation of the amorphous structure. Here we present results demonstrating an improved plasticity for a Cu45Zr45Al5Ag5 bulk metallic glass alloy rejuvenated by severe plastic deformation via high-pressure torsion (HPT). Nanoindentation as well as atomic force microscopy measurements performed on the cross-section of HPT samples provide evidence for the enhancement in plasticity. A robust algorithm developed to reliably detect and quantify the discontinuities (pop-ins) in the nanoindentation load–displacement curves is applied to a large dataset. The results related to the rejuvenated structure demonstrate (i) a reduction of the number of detectable pop-ins as well as (ii) a reduction of their displacement offset. Furthermore, (iii) a pronounced increase in the total creep value is observed and correlates with a plasticity criterion as well as a reduced hardness and Young’s modulus that are heterogeneously distributed across the samples due to localized strain softening during HPT. Finally, (iv) atomic force microscopy topographies obtained from selected indents support the findings, showing less pronounced steps in the plastic pile-up. The experimental results indicate that rejuvenation by HPT processing leads to structural and dynamical heterogeneities, increased atomic mobility and an improved plastic deformation response.

SEM and AFM analysis of the shear bands in Zr-based BMG after HPT

The surface relief formed by shear bands in bulk metallic glasses (BMG) under high-pressure torsion (HPT) has been investigated by the method of scanning electron microscopy (SEM) and atomic force microscopy (AFM). For this purpose, two halves of disks of the bulk metallic glass were jointed together and processed by HPT. The SEM examination of the internal surfaces of two joint halves of an HPT-processed disk allowed to study the formation and accumulation of shear bands under an increased imposed strain. The maximum density of the shear bands is observed at the edges of the HPT samples and in areas adjacent to the upper anvils. The observed minimum shear band spacing is equal to 0.5 μm after HPT processing for 5 revolutions.

Dynamic high pressure torsion: A novel technique for dynamic severe plastic deformation

Abstract Severe plastic deformation (SPD) processing of polycrystalline metals is often used to obtain ultra-fine grained and nano-crystalline microstructures. Increasing the strain rate during the SPD process is known to have a favorable effect on both grain fragmentation and mechanical properties, mainly through its effect on dislocation densities and twinning. However, dynamic SPD is barely explored, mainly because of the lack of suitable experimental techniques. In the present paper, a novel dynamic high pressure torsion facility is presented which imposes a dynamic, torsional deformation to a sample subjected to high hydrostatic pressure. The setup combines basic features of both split Hopkinson torsion bar (SHTB) and static high pressure torsion (HPT) devices. Torsional speeds up to 30,000 rpm can be reached, giving rise to strain rates in the sample up to 10,000/s. The first series of tests have been performed on commercially pure aluminum. The effect of DHPT processing on the mechanical properties and microstructure is evaluated by hardness and electron back-scatter diffraction measurements, respectively. The properties and microstructural features are compared with those obtained in conventional, statically deformed HPT samples.

Severe plastically deformed commercially pure aluminum: Substructure, micro-texture and associated mechanical response during uniaxial tension

Severe plastic deformation (SPD) of metals to obtain ultra-fine or even nano-sized grains has proven to be an interesting concept explored over the last few decades. However, the mechanical behavior of SPD metals and the underlying microstructural phenomena are not fully understood yet. In present work, commercially pure aluminum was subjected to high pressure torsion (HPT) deformation with strains ranging from very low levels to values well in the steady-state microstructure regime. The mechanical properties of the HPT processed samples were determined using tensile tests on miniature samples using full-field strain mapping. Orientation imaging microscopy (OIM) was utilized to follow the progression of grain refinement and texture as a function of imposed SPD. Local orientation based misorientation gradients helped to perform statistical boundary analysis and determine the fractions of incidental and geometrically necessary dislocation (GND) boundaries and local GND densities.From probability density distributions of the misorientation gradients two different stages of microstructural evolution, namely, fragmentation and saturation, could be discerned. The strength increased monotonously and the uniform elongation, though lower than the value of the annealed material, enhanced with the imposed strain in HPT. The post-necking response was observed to be highly microstructure dependent, where a lower grain size augmented the resistance for micro-crack propagation and enhanced the elongation-to-failure. In addition, the work hardening response corresponding to the yield point displayed maxima coinciding with the onset of the saturation stage. Anisotropy in fracture strain, observed between the axial and radial directions in a disk-like HPT sample, reduced with the randomization of shear texture, while higher intensities of the C {100}<110> orientation was considered responsible for the lower elongation-to-failure along the radial direction.

Sustainable and simple processing technique for n-type skutterudites with high ZT and their analysis

As various branches of industry are interested in good thermoelectric generators, there is a serious demand for an easy, fast, cheap and sustainable production route of excellent thermoelectric materials. In this paper we demonstrate how we could achieve a high-ZT (ZT ∼ 1.45 at 823 K) n-type bulk skutterudite, (Mm,Sm)yCo4Sb12, by processing the industrially produced raw powder using a modified high-pressure torsion (HPT) equipment at elevated temperature under inert gas. For this HPT processed sample as well as for the annealed one, structural properties, especially focused on grain size and dislocation density (backed up by electron probe microanalysis, transmission electron microscopy investigations as well as XPD profile analysis), physical properties (from 300 to 823 K and for the electrical resistivity in addition from 4.2 to 300 K) and mechanical properties (elastic moduli, hardness, fracture resistance) were measured and evaluated and compared with the values of a traditionally prepared bulk material, using hot pressing (HP). As a consequence of severe plastic deformation, we found a change from metallic to semiconducting behavior during measurement induced annealing of the HPT processed skutterudite, which could be explained via the change of lattice distortion and its influence on the band gap. A positive ZT net effect occurred because although the electrical resistivity was enhanced the thermal conductivity was decreased. It turned out that the elastic moduli of the HPT samples were not much different from those of the HP skutterudite, however, that the hardness was significantly increased.