Large negative magnetoresistance in capsulated Co–Cu powder prepared by mechanical alloying

Rattanasakulthong, Watcharee; Sirisathitkul, Chitnarong

doi:10.1016/j.physb.2005.08.010

Cited by 7 publications

(3 citation statements)

References 15 publications

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“…This isotropic MR is called GMR if the MR ratio reaches a magnitude of more than a few tens of percent. [93][94][95][96][97][98][99][100] The Cu-Co system is known as a good candidate for GMR as ferromagnetic Co particles with little solubility of Cu coexists in the Cu matrix. [101] A Cu-10wt%Co alloy was processed using HPT to achieve a fine dispersion of ferromagnetic particles and MR was reported at a level ∼ 2.5% at 77 K with an isotropic feature ( Figure 10).…”

Section: Giant Magnetoresistance (Gmr) Produced By Hptmentioning

confidence: 99%

Fundamentals of Superior Properties in Bulk NanoSPD Materials

Valiev

Estrin

Horita

et al. 2015

Materials Research Letters

298

136

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Bulk nanoSPD materials are materials with nanostructural features, such as nanograins, nanoclusters, or nanotwins, produced by severe plastic deformation (SPD) techniques. Such nanostructured materials are fully dense and contamination free and in many cases they have superior mechanical and functional properties. Here, we provide a critical overview of such materials, with a focus on the fundamentals for the observed extraordinary properties. We discuss the unique nanostructures that lead to the superior properties, the underlying deformation mechanisms, the critical issues that remain to be investigated, future research directions, and the application potential of such materials.

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Section: Giant Magnetoresistance (Gmr) Produced By Hptmentioning

confidence: 99%

Fundamentals of Superior Properties in Bulk NanoSPD Materials

Valiev

Estrin

Horita

et al. 2015

Materials Research Letters

298

136

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“…This requirement is very similar to the one for strengthening materials by particle dispersion except that the particles should be ferromagnetic. To achieve such a fine dispersion for GMR, several processes have been attempted such as thin film deposition following sputtering,9–11 meltspining from a molten alloy,12, 13 and mechanical milling of mixed powders 14–16. For most cases, supersaturation was attained and therefore subsequent postaging gave rise to a fine dispersion of ferromagnetic particles in the Cu matrix.…”

mentioning

confidence: 99%

High‐Pressure Torsion for Giant Magnetoresistance and Better Magnetic Properties

et al. 2010

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Processing through severe plastic deformation (SPD) leads to significant refinement of microstructures including the grain size and the dispersion of second phase particles. Among several SPD processes such as equal-channel angular pressing (ECAP), [1] high-pressure torsion (HPT), [2] accumulative roll bonding (ARB), [3] and multi-directional forging (MDF), [4] the process of HPT has advantages over the other SPD processes. Such advantages are that extremely large strain is introduced in the sample under very high pressure with an order of GPa, and therefore, finer microstructures are achieved in less ductile materials with neither breaking samples nor damaging tools (anvils and dies). Although there are many applications of the SPD processes for the enhancement of mechanical properties such as strength and ductility, the application is rather limited to functional properties related to magnetic and electric properties. [5][6][7][8] In this paper, we present an application of HPT to Cu alloys containing ferromagnetic Co and Fe particles. The importance underlining this approach is that regions of the second phase are fragmented to finely dispersed small particles and/or may be dissolved in the matrix to achieve supersaturation so that subsequent aging leads to a fine dispersion of precipitate particles. It is then shown that HPT is a potential process for producing giant magnetoresistance (GMR) in alloys prepared by conventional ingot metallurgy.The metallurgical requirement for a granular type of GMR is that ferromagnetic particles should be finely dispersed in the matrix of non-magnetic materials. This requirement is very similar to the one for strengthening materials by particle dispersion except that the particles should be ferromagnetic. To achieve such a fine dispersion for GMR, several processes have been attempted such as thin film deposition following sputtering, [9][10][11] meltspining from a molten alloy, [12,13] and mechanical milling of mixed powders. [14][15][16] For most cases, supersaturation was attained and therefore subsequent postaging gave rise to a fine dispersion of ferromagnetic particles in the Cu matrix. In this study, it is demonstrated that the HPT process should be an alternative for the production of GMR and this production is feasible using a bulk form of alloys prepared by conventional melting and casting procedures. ExperimentalAn ingot with a composition of Cu-10 wt%Co was prepared from high purity Cu (99.99%) and high purity Co (99.99%) using an arc-melting furnace in an argon atmosphere. Details were described in an earlier report [17] , but briefly, the ingot High-pressure torsion (HPT) was conducted on Cu alloys containing ferromagnetic Co and Fe particles. Electron probe microanalysis, X-ray diffraction analysis, and transmission electron microscopy confirmed that the particles were significantly refined through fragmentation and some fractions were dissolved into the Cu matrix with straining by HPT. Saturation magnetization decreases with straining and coercive force increa...

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“…Regarding the investigation of different magnetic properties of materials deformed by HPT, numerous studies focusing on the magnetic properties of HPT-processed materials are available [33][34][35][36][37][38][39][40][41][42]. Other techniques to apply severe deformation onto materials include ball milling, mechanical alloying, and equal channel angular pressing (ECAP), with some studies focusing on the magnetic properties of these alternative processing routes [18][19][20][21]26,43,44]. However, to the best knowledge of the authors, there are only two studies on HPT-deformed materials, which also contain information on magneto-resistive properties [34,37].…”

Section: Introductionmentioning

confidence: 99%

Tuneable Magneto-Resistance by Severe Plastic Deformation

Wurster

Weissitsch

Stückler

et al. 2019

Metals

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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.

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Large negative magnetoresistance in capsulated Co–Cu powder prepared by mechanical alloying

Cited by 7 publications

References 15 publications

Fundamentals of Superior Properties in Bulk NanoSPD Materials

Fundamentals of Superior Properties in Bulk NanoSPD Materials

High‐Pressure Torsion for Giant Magnetoresistance and Better Magnetic Properties

Tuneable Magneto-Resistance by Severe Plastic Deformation

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