scholarly journals Tuneable Magneto-Resistance by Severe Plastic Deformation

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1188 ◽  
Author(s):  
Stefan Wurster ◽  
Lukas Weissitsch ◽  
Martin Stückler ◽  
Peter Knoll ◽  
Heinz Krenn ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Pressure Torsion ◽  
Processing Parameters ◽  
Ferromagnetic Phase ◽  
Room Temperature Resistivity ◽  
Small Particles ◽  
Bulk Specimen ◽  
Binary Powder Mixtures ◽  
Magneto Resistance

Bulk metallic samples were synthesized from different binary powder mixtures consisting of elemental Cu, Co, and Fe using severe plastic deformation. Small particles of the ferromagnetic phase originate in the conductive Cu phase, either by incomplete dissolution or by segregation phenomena during the deformation process. These small particles are known to give rise to granular giant magneto-resistance. Taking advantage of the simple production process, it is possible to perform a systematic study on the influence of processing parameters and material compositions on the magneto-resistance. Furthermore, it is feasible to tune the magneto-resistive behavior as a function of the specimens’ chemical composition. It was found that specimens of low ferromagnetic content show an almost isotropic drop in resistance in a magnetic field. With increasing ferromagnetic content, percolating ferromagnetic phases cause an anisotropy of the magneto-resistance. By changing the parameters of the high pressure torsion process, i.e., sample size, deformation temperature, and strain rate, it is possible to tailor the magnitude of giant magneto-resistance. A decrease in room temperature resistivity of ~3.5% was found for a bulk specimen containing an approximately equiatomic fraction of Co and Cu.

Severe Plastic Deformation Processes with Friction Induced Shear

2010 ◽  
Vol 667-669 ◽  
pp. 25-30 ◽  
Author(s):  
Rimma Lapovok ◽  
Yuri Estrin ◽  
Richard Djugum ◽  
Andre Lerk
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Pressure Torsion ◽  
Processing Parameters ◽  
Two Dimensions ◽  
Work Piece ◽  
Special Group ◽  
Processed Material ◽  
Deformation Processes

Among the known severe plastic deformation (SPD) techniques, there is a special group of processes involving friction-induced shear. One of the sample or work-piece dimensions used in such processes, namely the thickness, is much smaller than the other two dimensions. The well-known process of High Pressure Torsion (HPT) and the relatively new Cone-Cone (CC) method applied to thin conical samples fall into this category of SPD techniques. Wrought aluminium alloy 2124 was used to study the effect of CC processing on microstructure and mechanical properties. The influence of the processing parameters, including the rotation speed and thickness of the conical strip specimens on the microstructure and the mechanical properties of the CC-processed material was investigated.

Bulk Ultrafine and Nanostructured Materials from Consolidation of Particles by Severe Plastic Deformation

2008 ◽  
Vol 579 ◽  
pp. 61-74 ◽  
Author(s):  
Kenong Xia
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Nanostructured Materials ◽  
High Pressure Torsion ◽  
Processing Parameters ◽  
Back Pressure ◽  
Angular Pressing ◽  
Important Processing

The progress in bulk ultrafine and nanostructured materials through consolidation of particles by severe plastic deformation (SPD) is reviewed. The focus is on the processes of high pressure torsion (HPT) and equal channel angular pressing (ECAP) with or without the application of a back pressure. Various materials consolidated are described in terms of their densities, microstructures and mechanical properties. The important processing parameters and their effects on the resulting materials are discussed. It is shown that SPD consolidation of particles is an effective way of producing bulk nanostructured materials although much work is needed to understand the consolidation behaviour and to design the optimum compositions and microstructures.

scholarly journals The Effect of the In-Situ Heat Treatment on the Martensitic Transformation and Specific Properties of the Fe-Mn-Si-Cr Shape Memory Alloys Processed by HSHPT Severe Plastic Deformation

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4621
Author(s):  
Carmela Gurau ◽  
Gheorghe Gurau ◽  
Felicia Tolea ◽  
Bogdan Popescu ◽  
Mihaela Banu ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
High Speed ◽  
High Pressure Torsion ◽  
Electron Interaction ◽  
Sudden Increase ◽  
Neel Temperature ◽  
Néel Temperature

This work focuses on the temperature evolution of the martensitic phase ε (hexagonal close packed) induced by the severe plastic deformation via High Speed High Pressure Torsion method in Fe57Mn27Si11Cr5 (at %) alloy. The iron rich alloy crystalline structure, magnetic and transport properties were investigated on samples subjected to room temperature High Speed High Pressure Torsion incorporating 1.86 degree of deformation and also hot-compression. Thermo-resistivity as well as thermomagnetic measurements indicate an antiferromagnetic behavior with the Néel temperature (TN) around 244 K, directly related to the austenitic γ-phase. The sudden increase of the resistivity on cooling below the Néel temperature can be explained by an increased phonon-electron interaction. In-situ magnetic and electric transport measurements up to 900 K are equivalent to thermal treatments and lead to the appearance of the bcc-ferrite-like type phase, to the detriment of the ε(hcp) martensite and the γ (fcc) austenite phases.

Role of Strain Gradient and Dynamic Transformation on the Formation of Nanocrystalline Structure Produced by Severe Plastic Deformation

2007 ◽  
Vol 539-543 ◽  
pp. 2787-2792 ◽  
Author(s):  
Minoru Umemoto ◽  
Yoshikazu Todaka ◽  
Jin Guo Li ◽  
Koichi Tsuchiya
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Strain Gradient ◽  
High Pressure Torsion ◽  
Large Strain ◽  
Nanocrystalline Structure ◽  
Angular Pressing ◽  
Dynamic Transformation ◽  
Fine Grained Structure

Formation of nanocrystalline structure by severe plastic deformation has studied extensively. Although ultra fine grained structure (grain size larger than 100 nm) had been obtained in many processes such as heavy cold rolling, equal channel angular pressing (ECAP) or accumulative roll bonding (ARB), the formation of nano grained structure (< 100 nm) is limited to processes such as ball milling, shot peening or drilling. In the present study, high pressure torsion (HPT) deformation and drilling were carried out to understand the conditions necessary to obtain nano grained structure in steels. The results of HPT experiments in pure Fe showed that HPT has superior ability of strengthening and grain refinement probably due to a strain gradient but the saturation of grain refinement occurs before reaching nano grained structure. Drilling experiments in high carbon martensitic steel revelaed that nano grained ferrite forms at the drilled hole surface only when the transformation from ferrite to austenite takes place during drilling. Considering various other processes by which nano grained ferrite was produced, it is proposed that heavy strains with large strain gradients together with dynamic transformation are necessary to reach nano grained ferrite structure.

Structure and Thermal Stability of Cu after Severe Plastic Deformation

2010 ◽  
Vol 297-301 ◽  
pp. 1312-1321 ◽  
Author(s):  
Vladimir V. Popov ◽  
A.V. Stolbovkiy ◽  
E.N. Popova ◽  
V.P. Pilyugin
Keyword(s):  
Thermal Stability ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Pressure Torsion ◽  
Pure Copper ◽  
Nanocrystalline Structure ◽  
Transmission Electron ◽  
Evolution Of Structure ◽  
Stability Of Structure ◽  
Thermal Stability Of

Evolution of structure of high-purity and commercially pure copper at severe plastic deformation (SPD) by high pressure torsion (HPT) at room temperature and in liquid nitrogen has been studied by transmission electron microscopy (TEM) and measurements of microhardness. Thermal stability of structure obtained by HPT has been investigated. Factors preventing from obtaining nanocrystalline structure in Cu are analyzed and possible ways of their overcoming are discussed.

scholarly journals Crystallization Features of Amorphous Rapidly Quenched High Cu Content TiNiCu Alloys upon Severe Plastic Deformation

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2670
Author(s):  
Alexander Glezer ◽  
Nikolay Sitnikov ◽  
Roman Sundeev ◽  
Alexander Shelyakov ◽  
Irina Khabibullina
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Copper Content ◽  
Melt Spinning ◽  
High Pressure Torsion ◽  
Amorphous State ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Cu Content ◽  
Rapid Melt Quenching

In recent years, the methods of severe plastic deformation and rapid melt quenching have proven to be an effective tool for the formation of the unique properties of materials. The effect of high-pressure torsion (HPT) on the structure of the amorphous alloys of the quasi-binary TiNi–TiCu system with a copper content of more than 30 at.% produced by melt spinning technique has been analyzed using the methods of scanning electron microscopy, X-ray diffraction analysis, and differential scanning calorimetry (DSC). The structure examinations have shown that the HPT of the alloys with a Cu content ranging from 30 to 40 at.% leads to nanocrystallization from the amorphous state. An increase in the degree of deformation leads to a substantial change in the character of the crystallization reflected by the DSC curves of the alloys under study. The alloys containing less than 34 at.% Cu exhibit crystallization peak splitting, whereas the alloys containing more than 34 at.% Cu exhibit a third peak at lower temperatures. The latter effect suggests the formation of regions of possible low-temperature crystallization. It has been established that the HPT causes a significant decrease in the thermal effect of crystallization upon heating of the alloys with a high copper content relative to that of the initial amorphous melt quenched state.

Structure and Properties of Grain Boundaries in Submicrocrystalline W Obtained by Severe Plastic Deformation

2009 ◽  
Vol 283-286 ◽  
pp. 629-638 ◽  
Author(s):  
Vladimir V. Popov ◽  
Ruslan Valiev ◽  
E.N. Popova ◽  
A.V. Sergeev ◽  
A.V. Stolbovsky ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Grain Boundaries ◽  
High Pressure Torsion ◽  
Submicrocrystalline Structure ◽  
Emission Mössbauer Spectroscopy ◽  
Structure And Properties ◽  
Initial State

Submicrocrystalline structure of W obtained by severe plastic deformation (SPD) by high pressure torsion (5 revolutions of anvils at 4000C) and its thermal stability have been examined by TEM. Grain boundaries of submicrocrystalline W have been studied by the method of the emission Mössbauer spectroscopy in the initial state and after annealing at 400-6000С.

Reversible Martensitic Transformation Produced by Severe Plastic Deformation of Metastable Austenitic Steel

2013 ◽  
Vol 738-739 ◽  
pp. 491-495 ◽  
Author(s):  
Igor Litovchenko ◽  
Alexander Tyumentsev ◽  
Alexander V. Korznikov
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Martensitic Transformation ◽  
Severe Plastic Deformation ◽  
Dynamic Recrystallization ◽  
Austenitic Steel ◽  
High Pressure Torsion ◽  
Martensitic Transformations ◽  
Metastable Austenitic Steel ◽  
Nanostructured States

The peculiarities of martensitic transformations and formation of nanostructured states in metastable austenitic steel (Fe-18Cr-8Ni-Ti) after severe plastic deformation by high pressure torsion are investigated. It is shown that during severe plastic deformation with increased strain rate not only direct (γ→α΄) but also reverse (α΄→γ) martensitic transformations occur, which is revealed by the changes in the volume content of α΄ - martensite during deformation. The fragments thought to be formed by direct and reverse martensitic transformations and those of dynamic recrystallization of austenite are observed.

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