Top PDF The electrical and magnetic properties of amorphous Pd-Cu-P alloys

The electrical and magnetic properties of amorphous Pd-Cu-P alloys

The electrical and magnetic properties of amorphous Pd-Cu-P alloys

The phonon modification of the density of states with temperature is suggested to be the cause of the observed negative temperature coefficients of resistivity in[r]

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Electrical and Magnetic Properties, and Electronic Structures of Pseudo Gap Type Antiferromagnetic L10 Type MnPt Alloys

Electrical and Magnetic Properties, and Electronic Structures of Pseudo Gap Type Antiferromagnetic L10 Type MnPt Alloys

In the present paper, we have carried out systematic investigations for electrical resistivity, magnetic susceptibil- ity and electronic specific heat coefficient. Especially, we added new data for low temperature region to the preliminary results 33) in order to discuss the electrical and magnetic properties as well as the theoretical results for the present alloy system. For detailed discussion of the correlation between the antiferromagnetic stability and the electronic state for the L1 0 type MnPt alloy system and their variation with the Pt composition, the electronic structures have been calculated by using the tight-binding linear muffin-tin orbital (LMTO) method with the coherent potential approximation (CPA) in the off-equiatomic composition. Furthermore, the LMTO band calculations including the spin–orbit interaction were performed in order to investigate the magnetocrystal- line anisotropy energy (MAE) because the MAE in the antiferromagnetic materials plays an important role in the exchange biasing-field in spin valves. 21) Furthermore, the theoretical calculations of the MAE give the reason why the magnetic phase diagram of the MnPt alloy system is rather complicated, compared with that of other L1 0 -type Mn alloy
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Influence of composition on the structure, electric and magnetic properties of Pd Mn P and Pd Co P amorphous alloys

Influence of composition on the structure, electric and magnetic properties of Pd Mn P and Pd Co P amorphous alloys

unable to establish a long-range magnetic order and a peak in the magnetization shows up at the lowest temperature range.. The electrical resistivity of Pd-Co-P s[r]

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The thermal and magnetic properties of the Fe89.8Ni1.5Si5.2B3C0.5 and Fe81B13Si14C2 amorphous alloys

The thermal and magnetic properties of the Fe89.8Ni1.5Si5.2B3C0.5 and Fe81B13Si14C2 amorphous alloys

Keywords: Thermal properties, Magnetic properties, Initial magnetization curve, Hystеresis loops, Total power core losses. 1. Introduction Iron based amorphous and nanocrystalline alloys are well established commercial soft-magnetic materials as their properties ratio vs. prices is well acceptable in common electrical devices. There are still intensive research efforts of their sensors effects as a single used ribbon [1, 2] or as a combination of amorphous ribbon with piezofiber [3, 4] or magnetostrictive [5] laminates as a new generation of multifunctional materials.
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Magnetic and Electrical Properties of Gd Doped Ni Cu Zn Fe2O4

Magnetic and Electrical Properties of Gd Doped Ni Cu Zn Fe2O4

Keywords Ni-Cu-Zn-Gd Nanoferrites, Magnetic Properties, Electrical Properties 1. Introduction Spinel Ni-Cu-Zn ferrites are one of the potential materials used in high fre- quency applications and in magnetic storage devices [1]. They are used as re- cording heads, inductors, deflection yokes, transformer cores, etc. [2] [3]. These ferrites with different chemical compositions in different forms like, thin films and nano powder have been investigated for their structural, electrical and mag- netic properties in recent years. In these ferrites, if partial doping of +2, +3 ions are replaced in the place of Fe 3+ ions, it may lead to the structural distortion the- reby enhancing the magnetic properties. Rare earth doped Ni-Cu-Zn ferrites re- sults in the improved magnetic and optical properties [4] [5] [6] [7] [8]. Higher percentage of rare earth doping in ferrites usually contributes for the formation How to cite this paper: Srinivasa Rao,
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Influence of Composition on the Structure and Properties of Fe Pd P and Ni Pd P Amorphous Alloys

Influence of Composition on the Structure and Properties of Fe Pd P and Ni Pd P Amorphous Alloys

INFLUENCE OF COMPOSITION ON THE STRUCTURE AND PROPERTIES OF Fe Pd P AND Ni Pd P AMORPHOUS ALLOYS Thesis by Philippe Louis Maitrepierre In Partial Fulfillment of the Requirements For the Degree of Doct[.]

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Thermodynamic Assessment of Fe B P Cu Nanocrystalline Soft Magnetic Alloys for Their Crystallizations from Amorphous Phase

Thermodynamic Assessment of Fe B P Cu Nanocrystalline Soft Magnetic Alloys for Their Crystallizations from Amorphous Phase

symbol E decreases to that at symbol H, although the corresponding compound phases are not drawn in Fig. 5. Here, it should be noted that Fig. 5 is valid for evaluating crystallizations with G only if the crystallizations take place along the composition lines parallel to the x-axes and that symbol A only exists on the vertical section diagrams. In other words, symbols DA, EA and H give the actual G values upon crystallizations, but these G values are the projected ones onto Fig. 5 just for reference. The actual contents of the metastable phases are summarized in Table 4 and the values of G of the metastable and stable phases are listed in Tables 4 and 5 where these phases are not necessarily plotted on the vertical section diagrams in Fig. 5. These are the short- comings of Fig. 5, but, in turn, the crystallization schemes of quaternary Fe-B-P-Cu alloys can be described compre- hensively in Fig. 5. With permitting the shortcomings of Fig. 5, the analysis was carried out based on Fig. 5 for the Fe 85.8 B 4.5 P 9 Cu 0.7 at T = 647 K and Fe 83.3 B 7 P 9 Cu 0.7 at T = 678 K, where both temperature are T x1 ’s. Figure 5 demonstrates the crystallization schemes with decreasing in G. At T x1 for the primary crystallization, the amorphous single phase was at the level of A on the G amor with a potential to equilibrate between bcc-Fe and remaining amorphous phase (B­C). Here, it should be noted that in reality remaining amorphous phase shown with symbol C in Fig. 5 is composed of dual Fe-rich amorphous alloys that are further enriched in B and P as shown in Table 4 at T x1 . The dual amorphous phases in Table 4 cannot be expressed in Fig. 5, and thus, Amor#1 and Amor#2 are regarded as a
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Crystallization, Transport and Magnetic Properties of the Amorphous (Fe1–xMnx)75P15C10 Alloys

Crystallization, Transport and Magnetic Properties of the Amorphous (Fe1–xMnx)75P15C10 Alloys

Crystallization, Transport and Magnetic Properties of the Amorphous (Fe 1–x Mn x ) 75 P 15 C 10 Alloys Md. Kamruzzaman 1* , Md. Abu Sayem Karal 2 , Dilip Kumar Saha 3 , Feroz Alam Khan 2 1 Department of Physics, Begum Rokeya University, Rangpur, Bangladesh; 2 Bangladesh University of Engineering and Technology (BUET), Dhaka, Bangladesh; 3 Materials Science Division, Atomic Energy Center, Dhaka, Bangladesh.

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Soft Magnetic Properties of Nanocystalline Fe Si B Nb Cu Rod Alloys
Obtained by Crystallization of Cast Amorphous Phase

Soft Magnetic Properties of Nanocystalline Fe Si B Nb Cu Rod Alloys Obtained by Crystallization of Cast Amorphous Phase

Figure 3 shows the X-ray diffraction patterns of the 1%Cu- containing alloy rod annealed for 300 s at 883 K and 600 s at 1073 K corresponding to the peak temperatures of the first- and third-exothermic peaks, respectively. The X-ray diffrac- tion patterns are identified as bcc-Fe + amorphous phases for the former sample and bcc-Fe + Fe 23 B 6 + Fe 2 B + Fe 3 Si + Fe 2 Nb phases for the latter sample, indicating that the crys- tallization reaction proceeds in the multi-stage process includ- ing the primary precipitation phase of bcc-Fe even for the rod sample. Figure 4 shows bright- and dark-field TEM images and selected-area electron diffraction of the mixed bcc-Fe and amorphous phases in the rod sample. It is seen that bcc-Fe grains with a particle size of about 10 nm disperse homoge-
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Phase Transformation and Magnetic Properties of Ferromagnetic Cu Mn Ga Alloys

Phase Transformation and Magnetic Properties of Ferromagnetic Cu Mn Ga Alloys

1 Depertment of Production Systems Engineering, Faculty of Engineering, Toyohashi University of Technology, Toyohashi 441-8580, Japan 2 Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8557, Japan Phase transformation, microstructure and magnetic properties were investigated for Cu-(11-14) mol%Mn-20 mol%Ga. The structures of the magnetic domains were also investigated by Lorentz microscopy and electron holography. Plate-like martensite phase( M , ordered hcp) was observed in as-quenched Cu-12 mol%Mn-20 mol%Ga. Phase transformation from M martensite to phase(hcp) occurred at around 540 K on heating. The phase decomposed into 00 (ordered hcp) and (bcc) phase at around 700 K, then became the single phase at around 840 K. By subsequent slow cooling, phase was observed at room temperature. The results obtained from Lorentz microscopy and electron holography revealed that the twin plates of M martensite and the magnetic domain have one-to-one correspondence, suggesting high magneto-crystalline anisotropy energy of the martensite phase. The saturation magnetization and the Curie temperature increased with Mn content.
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Martensitic Transformation and Magnetic Properties of Cu Ga Mn β Alloys

Martensitic Transformation and Magnetic Properties of Cu Ga Mn β Alloys

2 Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan 3 CREST, Japan Science and Technology Agency, Tokyo 105-6218, Japan The martensitic transformation and magnetic properties of Cu-Ga-Mn alloys were investigated. The alloys in the composition range Cu- 21 at%Ga-(13–15)at%Mn were found to exhibit a thermoelastic martensitic transformation from an L2 1 parent to a 2H martensite in the ferromagnetic state. This martensitic transformation disappeared with the precipitation of the ! phase induced by aging at room temperature.
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Magnetic States in Amorphous Pd (41)Ni (41)B (18) Alloys Containing Chromium and Iron

Magnetic States in Amorphous Pd (41)Ni (41)B (18) Alloys Containing Chromium and Iron

MAGNETIC STATES IN AMORPHOUS Pd 41 Ni 41 B 18 ALLOYS CONTAINING CHROMIUM AND IRON Thesis by Victor K C Liang In Partial Fulfillment of the Requirements For the Degree of Doctor of Philosophy Californi[.]

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Soft magnetic amorphous and nanocrystalline Fe-based alloys

Soft magnetic amorphous and nanocrystalline Fe-based alloys

Subsequently, the samples were thermally treated under vacuum at different temperatures in the range from 295-1123 K. The influence of different stoichiometry of the Fe-Ni-Si-B-C alloys on a thermal stability has been investigated by DSC technique. The as prepared samples of Fe 89.8 Ni 1.5 Si 5.2 B 3 C 0.5 and Fe 75 Ni 2 Si 8 B 13 C 2 alloy were thermally treated in the DSC cell at four heating rates: 5 Kmin -1 , 10 Kmin -1 , 20 Kmin -1 and 40 Kmin -1 . For both alloys, all DSC curves showed two well formed crystallization peaks indicating the multi-stage crystallization processes. However, the values of activation energy of the crystallization reaction determined by the Kissinger and Ozawa peak methods were some higher for the Fe 89.8 Ni 1.5 Si 5.2 B 3 C 0.5 alloy. In order to understand the crystallization mechanisms, analyses of the XRD patterns of each alloy heated isothermally at different temperatures, before and above the crystallization peaks in the DSC scan were performed. It was found that the onset of crystallization for the Fe 89.8 Ni 1.5 Si 5.2 B 3 C 0.5 amorphous alloy started at 753 K. XRD study of the Fe 75 Ni 2 Si 8 B 13 C 2 alloy revealed slightly earlier onset of crystallization in comparison with the Fe 89.8 Ni 1.5 Si 5.2 B 3 C 0.5 alloy. Namely, for the alloy with higher atomic contribution of Ni, Si, B and C, the thermally induced structural changes started already at 723 K.
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Relationship between Microstructures and Soft Magnetic Properties of Simultaneously P and Cu Added Fe Nb B Ribbon Alloys

Relationship between Microstructures and Soft Magnetic Properties of Simultaneously P and Cu Added Fe Nb B Ribbon Alloys

2 IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden, Germany The additional effect of P and Cu on the magnetic properties of Fe-Nb-B nanocrystalline soft magnetic alloys was investigated from the viewpoint of microstructures. Mean size of -Fe grain for both Fe 83:8 Nb 6:6 B 9:6 and Fe 83:7 Nb 6:6 B 8:6 P 1 Cu 0:1 ribbon alloys are measured to be about 8.5 nm, and size distribution of those are measured to be 0.391 and 0.236, respectively, using an oval approximation for shape of -Fe grains. Values of coercivity for Fe 83:8 Nb 6:6 B 9:6 and Fe 83:7 Nb 6:6 B 8:6 P 1 Cu 0:1 alloys calculated using a two-phase random anisotropy model are 6.73 and 4.93 Am 1 , and measured ones are 8.64 and 3.74 Am 1 , respectively. The improvement probably originates from the decrease in the distribution of the -Fe grain size in the crystallized structure by the simultaneous addition. [doi:10.2320/matertrans.MRA2008134]
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Magnetic Properties and Phase Transformations of
Bulk Amorphous Fe Based Alloys Obtained by Different Techniques

Magnetic Properties and Phase Transformations of Bulk Amorphous Fe Based Alloys Obtained by Different Techniques

The Fe-based amorphous alloys recently found by Inoue et al. 1–5) exhibit a large supercooled liquid region between the glass transition temperature T g and the crystallization temper- ature T x visible upon constant-rate heating to elevated tem- peratures. Because of the lack of crystalline anisotropy, they have good soft magnetic properties characterized by low co- ercive force and high permeability. 6–9) Nevertheless, residual anisotropy may be present, such as shape anisotropy or stress- induced anisotropy caused by internal mechanical stress in- duced by the preparation procedure, i.e. rapid quenching, slow cooling 9, 10) or ball milling. 11) The high glass-forming ability of this kind of alloys allows the formation of bulk glassy samples. 12) However, the critical cooling rate of about 10 2 K · s − 1 required for glass formation of these alloys limits the diameter of the samples. 13) The other hindrance that can influence bulk glass formation is the presence of impurities in the melt. 14, 15) When the conditions for glass formation are met (e.g. low impurity content, etc.) such alloys can be di- rectly cast in form of bulk specimens, which could be used for magnetic cores. Inoue and co-workers 16) reported that for FeAlGaPCBSi alloys ribbons with dimensions of up to 0 . 015 mm × 0 . 5 mm and cylinders up to a diameter of 3 mm can be prepared by melt spinning and copper mold casting, respectively. In the case of FeCrMoGaPCB alloys, Shen and Schwarz 15) used the flux-melting technique to remove the ox- ide inclusions from the melt and subsequent water quench- ing allows to produce rods with 4 mm diameter. The criti- cal cooling rate of about 10 2 K · s − 1 is higher compared to the
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Effects of P Addition on Corrosion Properties of Soft Magnetic FeSiB Alloys

Effects of P Addition on Corrosion Properties of Soft Magnetic FeSiB Alloys

4. Conclusions The amorphous Fe 76 Si 9 B 15 ¹ x P x (x = 0, 2, 5, 7, 10) ribbons with a width of 5 mm were prepared by the induction melting in the Ar atmosphere and the melt spinning in the open air condition. The electrochemical properties were investigated in the borate buffer solution of pH 8.45. The polarization curves of as-spun FeSiBP ribbons exhibited the lower current densities at lower applied potentials in comparison with Fe 76 Si 9 B 15 ribbon. This is thought to attribute to the bene fi cial role of a reaction product of iron phosphate at local active sites in the native oxide films. The Fe 76 Si 9 B 15¹x P x ribbon with x > 5 at% had good corrosion properties. The current densities of the samples after removal of oxide films decreased with the increasing P contents. The increase of P contents helps forming a double-layer passive film composed of an outer layer containing insoluble iron phosphate compounds and an inner layer containing Si-rich oxides.
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Electrical Resistivity and Mössbauer Studies for the
Structural Relaxation Process in Pd Cu Ni P Glasses

Electrical Resistivity and Mössbauer Studies for the Structural Relaxation Process in Pd Cu Ni P Glasses

and the Pd 40 Cu 30 Ni 9 Fe 1 P 20 alloys, the B 2 O 3 flux (99.999%) treatment was made in preparing them by arc melting. The Pd 42 . 5 Cu 27 . 5 Ni 10 P 20 alloy was flux-treated by holding it at 1300 K for 6 days in an evacuated quartz tube. Glass rib- bons, having cross sections of approximately 1 . 5 × 0 . 04 mm 2 for quaternary glasses and 5 . 0 × 0 . 05 mm 2 for Fe-doped glass, were prepared by conventional melt-spinning method with the peripheral velocity, approximately 20 m/s, of a copper wheel in an Ar gas atmosphere. The amorphous nature of samples was checked by X-ray diffraction using Cu–K α radiation and differential scanning calorimetry (DSC), operated at a heating rate of 0.67 K/s. The electrical resistivity measurement was performed by usual d.c four probes technique. The residual resistivity, ρ( 300 ) , at room temperature and the correspond- ing slope, ( d ρ/ dT ) 300 , were estimated by a least square fit to the resistivity data measured between 293 and 343 K af- ter a given heat treatment. The d.c current was supplied by a Rigaku R6161 source meter and it was so stable that the fluc- tuation was negligible during the experiment. The Keithley 182 nano-volt meter, having a precision within ± 50 nV, was used to measure the voltage change. The density of the bulk Pd 40 Cu 30 Ni 10 P 20 glass, prepared by water quenching, was measured at room temperature by Archimedes’ principle with a toluene as a working fluid.
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Influence of HPT Deformation on the Structure and Properties of Amorphous Alloys

Influence of HPT Deformation on the Structure and Properties of Amorphous Alloys

in the short-range order, the total amount, and the redistribution of free volume. Perhaps, structures produced by the SPD methods are in some aspects comparable to the nanoglass-type structures produced by IGC. Correspondingly, as a result of the HPT processing of amorphous alloys, essential transformations occur in their properties, in particular mechanical properties. For instance, as a result of preliminary HPT processing, the fracture fractography changes. Nanoindentation studies have shown that HPT processing leads to a significant increase in the values of the strain rate sensitivity in comparison with the initial state. At the same time, the course of change of the elastic modulus in a Zr-based BMG depends on the temperature of the HPT processing (20 or 150 °C). In some cases, HPT leads to a decrease in the values of Young’s modulus. The first work, indicating the emergence of tensile ductility in some BMGs (Zr 65 Al 7.5 Ni 10 Cu 12.5 Pd 5 ) after HPT processing, has been published. The emergence of tensile ductility can be explained by the formation of a high density of nanoscale inhomogeneities in the amorphous state. High tensile strength, high hardness, and low elastic modulus provide the great potential of BMGs for various commercial applications; however, these applications are limited by the brittleness of amorphous materials. Thus, a decrease in the elastic modulus and an increase in tensile ductility via HPT processing can provide wide applications for amorphous alloys.
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Magnetic Properties of bcc and bcc-fcc Fe-Pd Alloys Produce by Thermal Evaporation Technique

Magnetic Properties of bcc and bcc-fcc Fe-Pd Alloys Produce by Thermal Evaporation Technique

5. Conclusion In summary, Fe-Pd films of nanoscale thickness were grown by thermal evaporation. According to the XRD results, the film with 15 % at Pd is a solid solution with a bcc phase. The films with 20 and 36 % at Pd are solid solution with two phases bcc and fcc. The strong intensities of bcc (110) plane and fcc (111) planes could indicate a grain growth preferred orientation. According to SQUID results, films magnetization depends on Fe content and it decreases linearly with increasing Pd concentration. The presence of a second magnetic phase in films is observed by the coercivity films. This phase was also observed by Mössbauer spectrometry. According to Mössbauer results, the isomer shift and hyperfine field are proportional to the spin density and electron density at the nucleus for bcc phase.
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Crystallization kinetics and soft magnetic properties in metalloid-free (Fe,Co)90Zr10 amorphous and nanocrystalline alloys

Crystallization kinetics and soft magnetic properties in metalloid-free (Fe,Co)90Zr10 amorphous and nanocrystalline alloys

local Avrami exponents have been found for each individual process. Although Co-free alloy shows a larger grain size, crystalline fractions are similar for both alloys after equivalent annealing. Good soft magnetic properties at room temperature have been observed for amorphous and nanocrystalline alloy with x=30, which exhibits an amorphous Curie temperature of 735 K. The x=0 amorphous alloy is paramagnetic at room temperature and nanocrystalline samples exhibit a transition to superparamagnetic behavior.

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