Friction mode and shock mode effect on magnetic properties of mechanically alloyed Fe-based nanocrystalline materials (original) (raw)
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Magnetic properties of nanocrystalline Fe–10%Ni alloy obtained by planetary ball mills
Planetary ball mill PM 400 from Retsch (with different milling times for X = 400 rpm, x = 800 rpm) and P4 vario ball mill from Fritsch (with different milling conditions (X/x), X and x being the disc and the vial rotation speeds, respectively) are used for obtaining nanocrystalline Fe–10wt% Ni. The structure and magnetic properties are studied by using X-ray diffraction, SEM and hysteresis measurements, respectively. The bcc-Fe(Ni) phase formation is identified by X-ray diffraction. The higher the shock power and the higher milling time are, the larger the bcc lattice parameter and the lower the grain size. The highest value of the coercivity is 1600 A/m for Fe–10 wt.%Ni (with shock mode (424 rpm/100 rpm) after 36 h of milling), while the lowest value is 189 A/m for (400 rpm/800 rpm) after 72 h of milling. The milling performed in the friction mode has been found to lead the formation of alloys exhibiting a soft magnetic behavior for nanocrystalline Fe–10%Ni.
Fe–10 wt.% Ni and Fe–20 wt.% Ni alloys were prepared, using a planetary ball mill. The bcc Fe(Ni) phase formation is identified by X-ray diffraction after 36 h of milling. The higher the shock power, the larger the bcc lattice parameter and the lower the grain size. In the friction mode, the lower the crystallite size (11.1 ± 1.5 nm for Fe–10% Ni and 10.9 ± 1.5 nm for Fe–20% Ni), the lower the lattice strain (0.42 ± 0.05% for Fe–10% Ni and 0.43 ± 0.05% for Fe–20% Ni) for the following milling conditions: (Ω = 300 rpm/ω = 400 rpm) (Ω and ω being the disc and the vial rotation speeds, respectively). In the shock mode (corresponding roughly to the lowest values), the lower the crystallite size (10.2 ± 1.5 nm for Fe–10% Ni and 10.0 ± 1.5 nm), the higher the lattice strain (0.60 ± 0.05% for Fe–10% Ni and 0.67 ± 0.05% for Fe–20% Ni) for the following milling condition (424 rpm/100 rpm). The highest values of the coercivity have been found in the shock mode. Such highest values, have been found to be equal to 1600 A/m and 1420 A/m for Fe–10% Ni and Fe–20% Ni, respectively. The milling performed in the friction mode has been found to lead to the formation of alloys exhibiting a soft magnetic behavior for both Fe–10 wt.% Ni and Fe–20 wt.% Ni alloys.
Analysis of structure and magnetic properties of nanocrystalline milled alloys
Fe–20% Ni alloys were prepared using a planetary ball mill P4 vario ball mill from Fritsch (with different milling conditions (Ω/ω), Ω and ω being the disc and the vial rotation speeds, respectively). An artificial neural network (ANN) methodology was applied to rely the powder milling process parameters (Ω/ω) to the structure and magnetic properties of the Fe–20% alloys. An optimization procedure based on ANN training and testing steps was developed to predict structure and magnetic properties over a large range of process parameters. The following features have been anticipated: (i) In the friction mode process (FMP), the lower the crystallite size, the lower the lattice strain. (ii) In the shock mode process (SMP), the lower the crystallite size, the higher the lattice strain. (iii) FMP lead to the formation of alloys exhibiting a soft magnetic behavior (Hc between 380 A/m and 750 A/m) for Fe–20% Ni alloys. (iv) SMP lead to the formation of alloys exhibiting a memory and hard magnetic behavior (Hc = 900–1500 A/m) for Fe–20% Ni alloys.
Structure, magnetic and M¨ossbauer studies of mechanically alloyed Fe–20 wt.% Ni powders
Fe–20 wt.% Ni alloys were prepared using a planetary ball mill PM 400 from Retsch (with different milling times for Ω= 400 rpm, ω = 800 rpm) and P4 vario ball mill from Fritsch (with different milling conditions (Ω/ω), Ω and ω being the disc and the vial rotation speeds, respectively). The bcc-Fe(Ni) phase formation is identified by X-ray diffraction. The higher the shock power and the higher milling time are, the larger the bcc lattice parameter and the lower the grain size. The highest value of the coercive field is 1420 A/m for Fe–20 wt.% Ni (with shock mode (424 rpm/100 rpm) after 36 h of milling), while the lowest value is 110 A/m for (400 rpm/800 rpm) after 96 h of milling. The milling performed in the friction mode favors the formation of alloys exhibiting a soft magnetic behavior for Fe–20 wt.% Ni alloys. The M¨ossbauer spectra of the alloys recorded at 77 and at 300K differ according to the milling conditions and give relevant information on the local structure environment in relation with the nature of the mode used (friction or shock mode).
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.
The effect of milling speed on the structural properties of mechanically alloyed Fe–45%Ni powders
Journal of Alloys and Compounds, 2009
FeNi-based alloy powders are interesting in their applications as soft magnetic materials with low coercivity and high permeability. Their magnetic properties are closely related to their microstructure and particle size. In this study, nanocrystalline Fe-45%Ni alloy powders were prepared using a planetary ball mill. The effects of ball milling speed (the vial rotation speed (ω) and the disc rotation speed (˝)) on the microstructure and particle size of Fe-45%Ni alloy powders have been studied. The face-centered-cubic (FCC) ␥-(Fe, Ni) solid solution phase was identified by X-ray diffraction (XRD). The lattice parameter, lattice strain, grain size and quantitative amount of ␥-(Fe, Ni) phase have been estimated from Rietveld's powder structure refinement analysis of XRD data. The powder morphology and particle size were examined using scanning electron microscopy (SEM). The results showed that the FCC ␥-(Fe, Ni) phase could be observed completely at the vial rotation speed of 350 rpm and the milling time of 24 h. We also found that the higher milling speed leads to higher milling energy, larger lattice parameter, larger particle size and lower grain size of the investigated system.
Journal of Magnetism and Magnetic Materials, 2000
Fe 60 Mn 10 Al 20 Nb 10 , (Fe 60 Mn 10 Al 30 ) 95 Nb 5 and (Fe 60 Mn 10 Al 30 ) 90 Nb 10 ball milled powdered alloys were investigated using X-ray diffraction, Mössbauer spectrometry, thermomagnetic (TGM) and magnetization measurements. We studied the influence of Nb content and of different milling times on the structural and magnetic properties. Two main features can be concluded: (1) the FeAlMn induces a BCC phase whatever the Nb content is, and (2) as both increasing Nb content and milling time give rise to an highly disordered state in conjunction with a decrease of the ferromagnetic behavior.
X-ray diffraction and Mo¨ ssbauer studies of mechanically alloyed Fe–Ni nanostructured powders
Fe–10wt% Ni and Fe–20 wt% Ni nanostructured alloys were prepared using a planetary ball mill P 4 vario mill from Fritsch. The Fe (Ni) BCC solid solution was identified by X-ray diffraction, allowing also to follow the size and shape of crystalline grains. The higher the shock power, the smaller the grain size. The Mo¨ ssbauer spectra of the nanostructured powders recorded at 77 and 300K differ according to the shock power and the friction energy component while the hyperfine structure gives relevant information on the local structure environment of Fe atoms in relation with the milling mode process (shock or friction mode).
Development of nanocrystalline Fe–Co alloys using mechanical alloying
Materials Science and Technology, 2005
Nanostructured alloys have considerable potential as soft magnetic materials. In these materials a small magnetic anisotropy is desired, which necessitates the choice of cubic crystalline phases of Fe, Co, Ni, etc. In the present work, Fe-50 at.-%Co alloys were prepared using mechanical alloying (MA) in a planetary ball mill under a controlled environment. The influence of milling parameters on the crystallinity and crystal size in the alloys was studied. The particle size and morphology were also investigated using SEM. In addition, a thermal treatment was employed for partial sintering of some of the MA powders. The crystal size in both MA powders and compacted samples was measured using X-ray diffraction. It was shown that the crystal size could be reduced to less than 15 nm in these alloys. The nanocrystalline material obtained was also evaluated for magnetic behaviour.
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.