The structure and magnetic properties of magnetically soft cobalt base nanocrystalline powders and nanocomposites with silicon binding (original) (raw)
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Journal of Magnetism and Magnetic Materials, 2017
The present work deals with the development of nanocrystalline 60Co-26Fe-14Al (wt%) soft magnetic materials via mechanical milling of elemental powders. The evolution of solid solution during milling proceeded with continuous decrease in atomic order and the crystallite size, and an introduction of internal strain and dislocations. The milling-induced lattice defects, crystallite size reduction, and atomic disorder exhibited a decrease in saturation magnetization, remanence magnetization, squareness ratio, and blocking temperature with increasing milling time. It has been demonstrated that, at subzero temperatures, the magnetization decreases with increasing temperature due to the development of an effective anisotropy caused by an evolution of canted spin structure owing to the introduction of lattice defects during milling.
Structure and magnetic properties of powder soft magnetic materials
2007
AbstrAct Purpose: The paper presents influence of high-energy mechanical milling process, isothermal annealing and to a combination of these two technologies of cobalt base metallic glasses Co 77 Si 11.5 B 11.5 on magnetic properties and their structure. Design/methodology/approach: The powder test piece obtained from the input amorphous ribbon in highenergy ball milling. The diffraction examinations and examinations of thin foils were made on the JEOL JEM 200CX transmission electron microscope. Observations of the structure of powders were made on the Opton DSM-940 scanning electron microscope. The X-ray tests were realized with the use of the XRD 7 SEIFERT-FPM diffractometer. Findings: analysis of the magnetic properties test results of the of the Co 77 Si 11.5 B 11.5 powders obtained in the high-energy ball of milling process proved that the process causes significant decrease in the magnetic properties. The structure and magnetic properties of this material may be improved by means of a proper choice of parameters of this process as well as the final thermal treatment. Research limitations/implications: For the powders, further magnetical, structure and composition examinations are planed. Practical implications: The amorphous and nanocrystalline metal powders obtained by high-energy ball milling of metallic glasses feature an alternative to solid alloys and make it possible to obtain the ferromagnetic nanocomposites, whose shape and dimensions can be freely formed. Originality/value: The paper presents influence of parameters of the high-energy ball milling process on structure and magnetic properties of soft magnetic powder materials obtained in this technique. Results and a discussion of the influence of high energy mechanical milling process on particle size and their distribution as well as structure and magnetic properties of investigated samples is presented.
Influence of temperature on structure and magnetic properties of powders alloys
2007
Purpose: The paper presents the research results of nanocrystalline powders obtained by high energetic milling of amorphous ribbons based on cobalt Co77Si11,5B11,5 and Co68Fe4Mo1Si13,5B13,5. Design/methodology/approach: A 8000 SPEX CertiPrep Mixer/Mill high energy ball mill was applied to mill the ribbons both in „as quenched” state and heat treated. Observations of the structure of powders were made on the Opton DSM-940 scanning electron microscope. The change of powder material structure was measured with electron transmitting microscope JEOL JEM 200CX and X-ray analysis. The X-ray tests were realized with the use of the XRD 7 SEIFERT-FPM diffractometer. Findings: The analysis of the magnetic properties test results of the of the Co77Si11.5B11.5 and Co68Fe4Mo1Si13,5B13,5 powders obtained in the high-energy ball of milling process proved that the process causes significant decrease in the magnetic properties. The structure and magnetic properties of this material may be improved by means of a proper choice of parameters of this process as well as the final thermal treatment. Research limitations/implications: For the powders, further magnetical, structure and composition examinations are planed. Practical implications: The amorphous and nanocrystalline powders of Co77Si11,5B11,5 and Co68Fe4Mo1Si13,5B13,5 alloys obtained by high-energy ball milling of metallic glasses feature an alternative to solid alloys and make it possible to obtain the ferromagnetic nanocomposites, whose shape and dimensions can be freely formed. Originality/value: The paper presents influence of annealing temperature and parameters of the high-energy ball milling process on structure and magnetic properties of soft magnetic powder materials obtained in this technique. Results and a discussion of the influence of high energy mechanical milling process on particle size and their distribution and annealing temperature of powders as well as structure and magnetic properties of investigated samples is presented. According to achieved results it has been attempted to describe the possibilities of improvement the soft magnetic properties of obtained powder materials
Advanced Powder Technology, 2014
The main aim of this research is to fabricate the nano-crystalline Fe-Co-Si alloy with superior magnetic properties to be used in producing soft magnetic composites. The alloy powders were prepared by using a planetary ball mill. Morphological, structural and magnetic evolutions during milling were analyzed by scanning electron microscopy coupled with Energy-dispersive X-ray microanalyzer, X-ray diffractometer and vibrating sample magnetometer. The results confirm the production of the Fe(Co) and Fe(Co, Si) solid solutions after milling. Increasing the milling time did lead to smaller crystallite sizes and lattice parameters, but larger amounts of micro-strain and dislocation density. The magnetic measurements indicate that higher amounts of Si lead to lower values of saturation magnetization. The variations of coercivity could be attributed to the introduction of dislocations and reduction of crystallite size as a function of milling time.
Magnetic properties of hot pressed powder Co68Fe4Mo1Si13.5B13.5 alloy
2007
Purpose: The aim of the work is to investigate the structure and magnetic properties of the cobalt based hot pressed Co68Fe4Mo1Si13.5B13.5 powder obtained in high-energy ball milling process. Design/methodology/approach: The nanocrystalline ferromagnetic powders were manufactured by high-energy ball milling of metallic glasses ribbons in as state. The hot pressing process was made on machine “Degussa”. Observations of the structure of die stampings were made on the OPTON DSM-940 scanning electron microscope. Graphical analyses of the obtained X-ray diffraction patterns, as well as of the HC=f(TA) relationship were made using the MICROCAL ORIGIN 6.0 program. Findings: The analysis of the magnetic properties and structure of the die stamping out that compared to the magnetic properties of the amorphous ribbons as their precursor, that hot pressing process deteriorates their magnetically soft properties. Research limitations/implications: For the metallic Co-based amorphous ribbons, further mechanical and structure examinations are planed. Practical implications: Structure and magnetic properties analysis of die stampings of powdered amorphous metallic ribbons is helpful to prepare this material by laboratory methods. Feature an alternative to commercial alloys and composite materials are the amorphous and nanocrystalline metal amorphous ribbons obtained by melt spinning technique and make it possible to obtain the new composite materials with best magnetic properties, which dimensions and shape can be freely formed Originality/value: The paper presents influence of hot pressing parameters process of metallic powdered ribbons on structure and magnetic properties of obtained die stampings.
Soft magnetic nanocomposite with powdered metallic ribbon based on cobalt and polymer matrix
Journal of Materials Processing Technology, 2005
Structure, magnetic and mechanical properties of the nanocrystalline composite material of the SILAME® type were tested. The composite material was obtained by solidification of the nanocrystalline powder obtained in the high-energy grinding of the initially crystallized Co68Fe4Mo1Si13.5B13.5 amorphous ribbon with the silicon polymer.The metallic powder was mixed with the silicon polymer in a different weight ratio and next the effect of Co68Fe4Mo1Si13.5B13.5 powder weight ratio on the magnetic and physical properties of the composite was investigated.Moreover, the powder was subjected to uniaxial compression, in which the pastille was obtained with the density of ρ = 5.78 g/cm3 was subjected to the isothermal annealing after examining its magnetic properties. Next, the magnetic properties were compared with the obtained powder, powder after compression, and the compressed powder after annealing. In addition the effect of the high-energy milling conditions were presented on the soft magnetic properties of powder material and the influence of the silicon matrix on the magnetic and mechanical properties of the composite cores.
Magnetic Properties Study Of Nanocrystalline Cobalt and Cobalt-Based Alloys
Journal of Metastable and Nanocrystalline Materials, 2000
The effect of Ball milling parameters on the microstructure and consequently on the magnetic properties has been studied. The combination of low values of the plateau rotation and the high vial velocities w can enhance the cubic phase formation. Coercivity and crystallite size exhibit both a regular and similar diminution when plateau rotation velocity and mechanical alloying time are increasing.
Advanced Powder Technology, 2014
Fe 1Àx Co x (x = 0.1, 0.15, 0.2, 0.25, 0.3 and 0.5) powders were prepared by different milling-annealing treatments, and magnetic properties were investigated based on microstructure. Elevated heating times led to an increase in crystallite size, and decrease in lattice parameter. Up to 20 min annealing, series 3 powders showed a decrease in microstrain 2.5 times more than series 2. The coercivity (H C ) of 1-step milled and 60 min annealed Fe 50 Co 50 alloys decreased rigorously from 60 Oe to 19 Oe due to strain relief (from 0.3% to 0.08%) and grain growth (from 30 nm to 40 nm). For series 2 alloys, the H C (up to 60 min heating) increased from 72 Oe to 90 Oe, and decreased (up to 100 min heating) to 70 Oe. Compared to series 1, extra milling treatment of series 2 causes an increase in magnetization saturation (M S ) due to completion of alloying and grain refinement. Also, compared to series 2, extra annealing treatment for series 3 resulted in larger values of M S caused by stain relief.
Materiali in Tehnologije, 2015
The early stages in the mechanical alloying of amount fractions x = 40 % cobalt (Co) and x = 60 % silicon (Si) powders were investigated using X-ray diffractometry (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA) and vibrating-sample magnetometry (VSM). After 2-8 h of ball-milling, the characteristic XRD peaks of the face-centered-cubic (fcc) Si and hexagonal close-packed (hcp) Co phases remained sharp without a cobalt-silicide phase. As the milling progressed, the particle size observed by SEM tended to reduce, being accompanied by smoother edges and a narrow size distribution. On the DTA curves, between 200°C and 1200°C, exothermic peaks indicated a ferromagnetic-to-paramagnetic transition, whereas endothermic peaks corresponded to the lattice recovery, the transition from a hcp to a fcc Co and melting. The longest milling of up to 8 h significantly increased the magnetic squareness and the coercive field.
Journal of Non-Crystalline Solids, 2020
This study was aimed to investigate the effect of substitution of Fe with Co, C, and Mo on the glass forming ability (GFA), crystallization behavior, and magnetic properties of Fe-B-SiP -Cu (Nanomet) alloy. The thermodynamic parameters, P HS and P HSS , were used to guide towards increased GFA. The P HSS enhanced from −2.04 kJ/mol for Nanomet to −4.83 kJ/mol for a Co 4 C 1 Mo 1 (at.%) substituted alloy. As a result, the critical quench rate reduced significantly, manifested as a drop of the required rotational speed from 3000 rpm to 2000 rpm. The temperature interval between two crystallization peaks enlarged for the substituted alloy, allowing a broader annealing range for nanocrystallization. The saturation magnetization (M S) and the coercivity (H C) were nearly maintained. This work confirms the relevance of the parameters P HS and P HSS to improve the GFA of the Nanomet alloy, and it is suggested that the same strategy can be applied for other alloys. nanocrystalline microstructure, high M S of 1.75-1.78 T and low H C of 6.7-10.4 A/m after annealing [11]. Similarly, Zhang et al. [12] investigated Fe 83.3−x Co x Si 4 B 8 P 4 Cu 0.7 (x = 0-40 at%) alloys and showed that the lowest H C (5 A/m), highest M S (195 Am 2 /kg) and low core loss of 0.32 W/kg (at 50 Hz and 1.5 T) were obtained for an alloy with 4 at% Co. Furthermore, Jia et al. [13] studied the effect of Mo addition on the GFA, thermal stability, microstructure, and magnetic properties of the Fe 85 Si 2 B 8 P 4 Cu 1 alloy. The Mo addition in the Fe 85 Si 2 B 8 P 4 Cu 1 alloy enhanced the GFA and thermal stability, and as a result, the critical thickness of the amorphous alloy increased from 14 μm to 20 μm. These results make it plausible that the addition of multiple elements might further improve the GFA, and consequently, increase the critical thickness to the advantage of Nanomet type alloys. The present work aims to investigate the effect of Co, C, and Mo addition on GFA and soft magnetic properties of the Nanomet alloy. The thermodynamical parameters P HS and P HSS were computed, which take into account enthalpy of chemical mixing, mismatch entropy, and configurational entropy, to guide the systematic improvement in GFA of