Amorphous phase formation in Fe-6.0wt%Si alloy by mechanical alloying
Acácio Antonio Mesquita Furtado1999, Scripta Materialia
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Effects of Milling Time, Si Content and Heat Treatment on Microstructure and Magnetic Properties of Mechanically Alloyed Fe-Si Powders
In this study, the effects of milling time, chemical composition and heat treatment on microstructure and magnetic properties of nanocrystalline Fe-Si (6.5-25 at.% Si) alloys prepared by mechanical alloying have been investigated. The results show that increasing the milling time or the Si content, decreases the lattice parameter and increases the internal microstrain. The prepared powders mainly consist of micron-sized particles with an average grain size of less than 20 nm. The specific saturation magnetization values are slightly less than those of single crystal or conventional Fe-Si alloys and decrease as Si content increases. The coercive force values of the nanocrystalline as-milled powders are much higher than those of corresponding Fe-Si bulk alloys with a minimum at 13.5 at. % Si. The values of coercive force decreased after annealing but it seams that the residual strain developed during milling is not the major contributing factor to the higher values of coercive force in the mechanically alloyed powders and nanocrystals behave as single-domain particles without exchange interaction between them.
Magnetic properties of mechanically alloyed Fe-Si
IEEE Transactions on Magnetics, 1990
We have prepared mechanically alloyed samples of FeNi, FeNi,, and (FeNi,),,Ag,. The production of nanometer size grains was confirmed by x-ray broadening and electron microscopy. X-ray measurements indicated that a small amount (-7%) of Ag could be alloyed into the Fe-Ni and that considerable lattice strain was present. Mossbauer and magnetic measurements found no evidence for superparamagnetism in these alloys. Samble PreDaration Elemental powders with a purity of 99.9% or better and a particle size in the range of 6 to 9 pm for iron, 4 to 7 pm for silver, and 20 to 45 pm for nickel were mixed in the desired proportion. Mechanical alloying was performed using SPEX 8000 Mills? with round-bottom hardened steel vials. For each sample, a total of 5 tReferences to commercial products are provided for infomation only and do not constitute an endorsement or recommendation 1717
Structural and magnetic properties of metastable Fe 1- x Si x (0.15< x <0.34) alloys prepared by a rapid-quenching technique
Journal of Physics: Condensed Matter, 2002
Fe 1−x Si x (0.15 < x < 0.375) alloys have been prepared by a rapidquenching technique. X-ray diffraction patterns show that these alloys consist of submicron grains between 100 and 300 nm. The DO 3 cubic symmetry could be obtained for Si content up to 34 at.% Si. This feature is particularly interesting since alloys containing more than 26 at.% Si and cast with usual techniques consist of a mixture of Fe 3 Si and Fe 5 Si 3 . The magnetization, Curie temperature and resistivity data for these fine-grained alloys are consistent with those for bulk alloys for Si content below 25 at.% Si. In contrast, the structural and physical data for single-phase alloys with 28-34 silicon content are reported for the first time. Within this composition range, the magnetization and Curie point values roughly correspond to those suggested by the extrapolation of existing data. However, the resistivity shows an unexpected marked increase above 25 at.% Si. The values of resistivity, magnetization and effective anisotropy of soft-magnetic nanocrystalline Fe 2 Si are found to be 200 µ cm, 0.6 T and 15 kJ m −3 respectively, suggesting that this alloy has potential for highfrequency applications.
Effect of chromium on microstructure, ordered phase and magnetic properties of Fe-6.5 wt%Si alloy
Effects of chromium additions on the microstructure, ordered phase and magnetic properties of the Fe-6.5 wt.% Si alloy fabricated by hot-rolling and warm-rolling were investigated. The results showed that the additions of chromium reduced the grain size of the alloy effectively, and the dislocation density was reduced with the increasing of the chromium content. The amount of ordered phase was reduced in the alloy with the chromium content of 1.0wt%. The magnetic properties of the alloy with chromium were not deteriorated. 1.Introduction Fe-6.5 wt%Si alloy has excellent soft magnetic properties, such as high permeability, low iron loss in the high frequency and near-zero magnetostriction. It has extensive application prospects in high frequency fields, including transformers, power generators and electric relay due to its advantages of reducing the energy consumption and noise pollution[1-3]. It also can be used in high temperature with its high Curie temperature of 973K. However, the ductility and workability of Fe-6.5 wt%Si alloy is very poor at room temperature, so it is very difficult to fabricate thin sheets by conventional cast-rolling process and seriously blocks its industrial production and application[4]. There are several other methods developed to obtain thin sheets of Fe-6.5 wt%Si alloy, such as chemical vapor deposition (CVD), spray forming, direct powder rolling (DPR), dipping and diffusion annealing, etc[5-9]. While most of the above methods are not suitable to produce wide sheet in commercial scale compared with cast-rolling process, and they all have many disadvantages such as long production cycle, and high production costs and air pollution. The brittleness of Fe-6.5 wt%Si alloy is related to the existence of B2 and DO3 ordered phase, the large size of the grain, impurity on grain boundary[10-11]. To improve the ductility of Fe-6.5 wt%Si alloy, many methods were tried, and alloying is one of the most popular methods. In this paper, different contents of chromium element were added into Fe-6.5wt%Si alloy, the sheets with the thickness of 0.3~0.4 mm were obtained after hot-rolling and warm-rolling. The microstructure of the alloys were observed by metallographic microscope and TEM,and the magnetic properties was measured. 2.Experimental procedures The Fe-6.5 wt%Si alloys in this research were produced by melting industrial pure iron (99.5wt.%), high purity silicon (99.9wt.%) and pure chromium (99.9wt.%) in a vacuum medium-frequency induction furnace, and then poured into ingot molds at 1550. Subsequently, the ingots were forged into a thickness of 20mm at a temperature range of 900-1100 to both reduce the casting defects and improve the homogenization and compaction of the alloy. Then the obtained slabs were continuously hot-rolled to a thickness of 1.0mm at 1000 with the deformation rate of each rolling pass more than 40%. Then the hot-rolled plates with a thickness of 1.0 mm were rolled at a temperature range of 600-700 to a final thickness of 0.2-0.3mm. The rolling process schedule of the alloys is shown in Figure 1.
Magnetic losses and mechanical properties of Fe-4 to 7.8 wt% Si rapidly quenched alloys
Magnetics, IEEE …, 1997
Mechanism of mechanical alloying phase formation and related magnetic and mechanical properties in the FeSi system
Journal of Alloys and Compounds, 1993
Based on X-ray diffraction (XRD) patterns, scanning electron microscopy (SEM) investigations, energy dispersive X-ray (EDX) chemical analysis, thermal analysis (DSC and DTA) and thermomagnetogravimetry (TMG) investigations, the far from equilibrium crystalline to amorphous phase transition induced by mechanical aIloying (MA) in the Fe-rich side of the Fe-Si system was studied. Starting from a mixture of Fe and Si powders, MA leads to an expansion (up to 16 wt.% Si) of the A2 crystalline disordered solid solution phase domain. ln this composition field an amorphous phase is also detected. For an Si content larger than 16 wt.% Si, a mixture of metastable phases (an amorphous and high temperature phases) and stable phases (low tempe rature phases) was detected. The crystalline to amorphous phase transition was a polymorphic phase transition which was attributed to instability of the crystalline lattice. The expansion of the A2 phase domain up ta 15 wt. % Si was confirmed by Vicker's microhardness measurements, as weIl as the starting of the ordering reaction A2-B2 above 16 wt. % Si and the existence of the D03 phase at 17 wt. % Si. The influence of the structural state and the grain size on the magne tic properties sucb as the coercive force and the saturation magnetization was also studied. A high coercive force value of 17.2 X 10 3 A m-1 at 1000 Hz frequency and 0.15 T magnetic induction was reported for the 5 wt. % Si composition sample. An increase in ductility and low hysteresis loop were observed for the 10 wt. % Si composition.
Magnetization Measurements on "as Prepared" and Annealed Fe 3-x Mn x Si Alloys
2008
Abstract: The magnetic properties of the alloy system Fe 3-x Mn x Si have been studied by measuring magnetization for samples with x = 0, 0.1, 0.25, 0.5, and by thermal scanning techniques for samples with x = 0, 0.1. The results reveal that the system is ferromagnetic in this composition range. Zero field cooling and field cooling magnetization measurements indicate a similar magnetic ordering and magnetic anisotropy in all samples. The saturation magnetization for the annealed samples was higher than that for "as prepared" samples. This is attributed to the reduction of magnetic domain boundaries rather than to improving magnetic order as a result of annealing. Further, T C values determined from thermal DSC measurements are in good agreement with previously reported results based on magnetic measurements.
Magnetization Measurements on "as Prepared" and Annealed Fe 3-x Mn x Si Alloys
The magnetic properties of the alloy system Fe 3-x Mn x Si have been studied by measuring magnetization for samples with x = 0, 0.1, 0.25, 0.5, and by thermal scanning techniques for samples with x = 0, 0.1. The results reveal that the system is ferromagnetic in this composition range. Zero field cooling and field cooling magnetization measurements indicate a similar magnetic ordering and magnetic anisotropy in all samples. The saturation magnetization for the annealed samples was higher than that for "as prepared" samples. This is attributed to the reduction of magnetic domain boundaries rather than to improving magnetic order as a result of annealing. Further, T C values determined from thermal DSC measurements are in good agreement with previously reported results based on magnetic measurements.
Magnetic properties of spray-formed Fe–6.5%Si and Fe–6.5%Si–1.0%Al after rolling and heat treatment
Journal of Magnetism and Magnetic Materials, 2008
The maximum silicon content in commercial Fe-Si steels is limited to about 3.5 wt%Si, since the ductility declines sharply as this maximum is exceeded, hindering the production of thin sheets by cold/hot rolling. However, the best magnetic properties are attained at about 6.5 wt%Si, a silicon content that renders magnetostriction practically null and minimizes magnetic losses. Using spray-forming, our research group has successfully produced this type of high silicon alloy in thin sheet form by carefully controlling the many variables of the process and subsequent rolling operations. In the present study, we investigated the magnetic properties and the microstructure of spray-formed Fe-6.5 wt%Si and Fe-6.5 wt%Si-1.0 wt%Al alloys after warm rolling and heat treatment. The main cause for the brittleness of Fe-6.5 wt%Si alloy has been attributed to the B2 phase long-range ordering, which leads to premature fractures. The presence of aluminum could avoid B2 formation and improve the alloy's ductility. The binary Fe-6.5 wt% Si alloy showed the best magnetic properties, which were ascribed to a recrystallized, coarse grain size (500 mm; and 340 mm for the Al-containing alloy). TEM analysis showed that a well-developed B2 domain structure (about 50-300 nm in size) was formed in the binary alloy when low cooling rates are prevailing after heat treatment. This structure contributed to improve additionally the magnetic properties, but its effect was not so strong as that of the grain size. The addition of Al to the binary alloy suppressed B2 formation, as indicated by Mossbauer spectroscopy, and apparently hindered excessive grain growth, which may explain the slightly poorer magnetic properties when compared with the binary alloy. r
Magnetic Properties and Crystallization of the Fe 75 Si 15 B 10 Amorphous Alloy Prepared by Mechanical Alloying
Hyperfine Interactions, 2000
The magnetic order and crystallization of the amorphous Fe 75 Si 15 B 10 alloy prepared by mechanical alloying was studied in situ by 57 Fe Mössbauer spectroscopy. These measurements were carried out using a vacuum furnace, controlling the temperature in the absorber. From Mössbauer measurements the magnetic order temperature of the as-milled sample was estimated at about 675 K. In order to identify the crystalline phases formed during heating, Mössbauer measurements were analyzed together with X-ray diffraction analysis. Both results show the formation of several crystalline phases such as Fe 5 SiB 2 , Fe 2 B, Fe 3 Si, α-Fe, Fe-B composite and a residual amorphous phase.
Synthesis of Fe–Si–B–Mn-based nanocrystalline magnetic alloys with large coercivity by high energy ball milling
Alloys of Fe–Si–B with varying compositions of Mn were prepared using high energy planetary ball mill for maximum duration of 120 h. X-ray diffraction (XRD) analysis suggests that Si gets mostly dissolved into Fe after 80 h of milling for all compositions. The residual Si was found to form an intermetallic Fe3Si. The dissolution was further confirmed from the field emission scanning electron microscopy/energy dispersive X-ray analysis (FE-SEM/EDX). With increased milling time, the lattice parameter and lattice strain are found to increase. However, the crystallite size decreases from micrometer (75–95 μm) to nanometer (10–20 nm). Mössbauer spectra analysis suggests the presence of essentially ferromagnetic phases with small percentage of super paramagnetic phase in the system. The saturation magnetization (Ms), remanance (Mr) and coercivity (Hc) values for Fe–0Mn sample after 120 h of milling were 96⋅4 Am2/kg, 11⋅5 Am2/kg and 12⋅42 k Am–1, respectively. However, for Fe–10Mn–5Cu sample the Ms, Hc and Mr values were found to be 101⋅9 Am2/kg, 10⋅98 kA/m and 12⋅4 Am2/kg, respectively. The higher value of magnetization could be attributed to the favourable coupling between Mn and Cu.
Mössbauer and xrd study of the Fe0.5 Si0.5 system produced by mechanical alloying and sinterization
Revista Mexicana De Fisica, 2012
Resumen en: In this work Fe0.5 Si0.5 samples were mechanically alloyed at different milling times. The sample milled during 48 hours presents the FeSi simple cubic a...
Correlation between structural parameters and magnetic properties of ball milled nano-crystalline Fe–Co–Si powders
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.
Thermal Analysis and Macrostructure of Fe-Si Alloys
The high electrical and magnetic properties that possess Fe-Si alloys makes them useful materials in the electricity sector as well as in new technological and energy applications. The effect of silicon addition in non-equilibrium transformations of Fe-Si alloys was analyzed via cooling curves analysis, macrostructural characterization and hardness profiles. Two alloys Fe-Si with commercial level impurities were produced by melting. The thermal history was recorded and analyzed throughout the solidification and cooling ranges for each alloy. Samples were sectioned for their characterization and then, resistance to plastic deformation was quantified through a hardness test. Results show that, small increases in the percentage of silicon alter the final morphology because to the presence of more transformations during cooling of samples caused by expansion of the gamma region.
Influence of energy density on the microstructure, growth orientation, and anisotropy of magnetic properties in additively manufactured Fe-3.8wt%Si transformer steels
Materialia, 2023
Fe-3.8wt%Si transformer steels were processed using two different additive manufacturing (AM) techniques, laser powder bed fusion (LPBF) and directed energy deposition (DED). While the LPBF processed samples exhibited a strong <001> orientation of the BCC grains along the build axis, the DED processed samples exhibited a randomized texture along the build axis. DED processed samples showed substantially coarser columnar grains as compared to their LPBF counterparts. The columnar grains exhibited a substantial number of low-angle sub-grain boundaries. All samples exhibited very good soft magnetic properties, with saturation magnetization (M s) values ranging from 205-232 emu/gm, and coercivity (H c) values ranging from 1.2-4.2 Oe. The Coercivity (H c) values were significantly lower when the magnetic field was applied parallel to the build axis, as compared to being perpendicular, which can be rationalized based on the columnar nature of the grains, resulting in a higher number density of grain boundaries in case of the field applied perpendicular to the build axis.
Magnetic and mechanical properties of rapidly solidified FeSi 6.5 wt% alloys and their interpretation
Journal of Magnetism and Magnetic Materials, 1996
The structural, mechanical and magnetic properties of Fe Si 6.5 wt% rapidly solidified alloys have been investigated following recrystallization annealing and different rates of cooling through the B 2 + DO 3 ordering region (1 _< 7~< 1500OCmin t). A transition from ductile to brittle behavior is observed for "F< -1000°Cmin i chiefly due to B 2 ordering and the associated formation of superlattice dislocations, having reduced glide and cross-slip capability. The magnetic behavior appears, however, to be weakly dependent on 7 ~, with the energy losses minimized for average grain size around 100-150 ~,m.
Contribution of the crystalline phase Fe/sub 100-x/Si/sub x/ to the temperature dependence of magnetic properties of FINEMET-type alloys
IEEE Transactions on Magnetics, 2000
The temperature dependence of the hysteresis loop, saturation magnetization, and saturation magnetostriction of rapidly quenched ribbons of the compositions Fe 100 Si ( = 12 1 13 8 20 0) and of FINEMET-type material with compositions Fe 73 5 Cu 1 Nb 3 Si 13 5 B 9 and Fe 73 5 Cu 1 Nb 3 Si 16 5 B 6 were measured between room temperature and 400 C. This paper analyzes the temperature dependence of the saturation magnetostriction and the saturation magnetization of the FINEMET ribbons after various heat treatments, assuming a superposition of the properties of the nanocrystalline Fe-Si and of the remaining amorphous phase. The behavior of the coercivity of Fe-Si prepared by rapid solidification follows roughly that of the (absolute value) of the magnetostriction. The Curie temperature of the remaining amorphous phase is enhanced.
Effect of the low temperature annealing on primary and secondary structures and magnetic properties of Fe-3% Si
Materials Research
The processing of 3% Si steel is characterized by the use of MnS particles as a normal grain growth inhibitor. Experiments were carried out to investigate the grain growth in this material during heat treatments at low temperature. Industrial decarburized samples ...
Effect of Si addition on AC and DC magnetic properties of (Fe-P)-Si alloy
AIP Advances, 2016
We report a new (Fe-P)-Si based alloy with relatively high induction (1.8-1.9 T), low coercivity (< 80 A/m), high resistivity (∼38 µΩ cm) and low core loss (217 W/kg @ 1 T/1 kHz) comparable to the commercially available M530-50 A5 Si-steel. The attractive magnetic and electrical properties are attributed to i) the two phase microstructure of fine nano precipitates of Fe 3 P dispersed in α-Fe matrix achieved by a two-step heat-treatment process and ii) Si addition enhancing the resistivity of the α-Fe matrix phase. As the alloy processing is by conventional wrought metallurgy method, it has the potential for large scale production.
ON THE AMORPHIZATION OF Fe-Si BY MECHANICAL ALLOYING
Le Journal de Physique Colloques, 1990
Un melanqe de poudres de Fe et Si (3:l en proportion atomiaue) a Cte moulu pendant des temps differents a l'aide d'un moulin planetaire a billes. On a realise des etudes de la microstructure'et des proprietes des materiaux ainsi prepares utilisant DRX, MEB, CDB et MEV. On a trouve des evidences de la formation de la solution solide Fe7sSi25 et de l'amorphisation partialle des materiaux prepares.
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Synthesis of Fe-Si-B-Mn-based nanocrystalline magnetic alloys with large coercivity by high energy ball milling
Bulletin of Materials Science, 2014
Alloys of Fe-Si-B with varying compositions of Mn were prepared using high energy planetary ball mill for maximum duration of 120 h. X-ray diffraction (XRD) analysis suggests that Si gets mostly dissolved into Fe after 80 h of milling for all compositions. The residual Si was found to form an intermetallic Fe 3 Si. The dissolution was further confirmed from the field emission scanning electron microscopy/energy dispersive X-ray analysis (FE-SEM/EDX). With increased milling time, the lattice parameter and lattice strain are found to increase. However, the crystallite size decreases from micrometer (75-95 μm) to nanometer (10-20 nm). Mössbauer spectra analysis suggests the presence of essentially ferromagnetic phases with small percentage of super paramagnetic phase in the system. The saturation magnetization (M s), remanance (M r) and coercivity (H c) values for Fe-0Mn sample after 120 h of milling were 96⋅4 Am 2 /kg, 11⋅5 Am 2 /kg and 12⋅42 k Am-1 , respectively. However, for Fe-10Mn-5Cu sample the M s , H c and M r values were found to be 101⋅9 Am 2 /kg, 10⋅98 kA/m and 12⋅4 Am 2 /kg, respectively. The higher value of magnetization could be attributed to the favourable coupling between Mn and Cu.
The Effect of B and Si Additions on the Structural and Magnetic Behavior of Fe-Co-Ni Alloy Prepared by High-energy Mechanical Milling
Journal of Superconductivity and Novel Magnetism, 2020
We investigate the structural and magnetic properties of nancrystalline Fe50Co25Ni15X10 (X=Bamorphous, Bcrystalline and Si) alloy powders prepared by mechanical alloying process. Morphological, microstructural and structural characterizations of the powders milled several times were investigated by scanning electron microscopy and X-ray diffraction. The final metallurgical state strongly depends on the chemical composition and the grinding time; it can be single-phase or two-phase. The crystallite size reduction down the nanometer scale is accompanied by the introduction of high level of lattice strains. The dissolution of Co, Ni, B (amorphous and crystalline) and Si into the α-Fe lattice leads to the formation of highly disordered Fe-based solid solutions. Coercivity (Hc) and the saturation magnetization (Ms) of alloyed powders were measured at room temperature by a vibration sample magnetization. The magnetic measurements show a contrasting Ms and (Hc) in all alloy compositions. Conclusively, soft magnetic properties of nanocrystalline alloys are related to various factors such as metalloids addition, formed phases and chemical compositions.
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