Structural and Mossbauer studies of mechanically prepared Fe70Cu30 alloy (original) (raw)
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Magnetic and structural properties of as-milled and heat-treated bcc-Fe70Cu30 alloy
Journal of Magnetism and Magnetic Materials, 1995
A ferromagnetic solid solution with a nomina] atomic composition FeroCUr~ and a body-cen~ structure has been obtained by high-energy ball milling. The decomposition of the system is monitored by X-ray diffraction (XRD), measurements and M~ssbauer spectroscopy. According to XRDo for heating lcmpe.~tures below 723 K there is only a bcc ph.".~e in the material, while fvr heating temperatures above 723 K a new phase, with a fcc structure, appears, suggesting lha~ the solid solution has decomposc'd into bce-Fe and fcc-Cu. However, the magnetic behavior observed during the decomposition process indicates that this evolution is more complex than the simple deeomposition into the equilibrmm phases. This behavior can be summarized in two points: (1) a decrease in the ma~-tization at 5 K, and (2) dra~Ii¢ cha~'cs in the coercive field with the thermal treatment, soft magnetic behavior for the matc~"ial in the as-milled sta~e, ~a~g~ netism for low heating temperatures and a hardening of the mat~al ~ to above 723 K, for which the va|~es of the coercive field at room temperature are several times higher than those for the as-milled sampte. The Mtissbat~r st~ctrosc~y performed at room temperature shows thai for the heat-u~ated samples ~i~ Fe atoms are in two differem phases: a ferromagnetic phase, which evolves to bcc-Fe, and a paramag,~et~: phase.
Journal of Alloys and Compounds, 2010
The mechanical alloying process has been used to prepare nanocrystalline Fe70−xCuxCo30 (x = 0, 3, 6, and 10) alloy from powder mixture. The structure and magnetic properties were investigated through powder X-ray diffraction (XRD), electron microscopy and magnetization measurements. The XRD patterns show a bcc crystal structure with lattice constant 0.2865 nm and crystallite size (D) of 15 nm evolves on 60 h milling in the case of Fe–Co alloy. But it is found that Cu speeds up the formation of bcc phase with finer microstructure (D = 7 nm for x = 10). Increase in microstrain is observed with the milling time and also with Cu concentration. The magnetic measurements show a contrasting saturation magnetization and coercivity (HC) for the case of samples having lower (x ≤ 3) and higher (x > 3) Cu content in Fe–Co alloys. These variations are explained on the basis of crystallite size and strain variations in the samples during milling. Present results indicate that a nonmagnetic inc...
Mechanically alloyed Cu–Fe studied by Mössbauer spectroscopy
Journal of Alloys and Compounds, 2001
Recent studies of mechanically alloyed Fe-Cu powder mixtures have suggested differences in the local magnetic environment of iron atoms. For a more accurate definition of this point, ball-milled Cu Fe and Cu Fe alloys were investigated by Mossbauer 70 30 50 50 spectroscopy in the temperature range 4.2-300 K. The low temperature Mossbauer spectra exhibit a broad magnetic pattern typical of a defect structural configuration. The magnetic splitting strongly decreases with increasing temperature, especially in the case of Cu Fe 70 30
Mössbauer study of alloy Fe67.5Ni32.5, prepared by mechanical alloying
2015
We present the study of effect of the particle size on the structural and magnetic properties of the Fe67.5Ni32.5 alloy, prepared by mechanical alloying (MA). After milling the powders during 10 hours they were separated by sieving using different meshes. The refinement of the X-ray patterns showed the coexistence of the BCC (Body Centered Cubic) and the FCC (Face Centered Cubic) phases in all samples with lattice parameters and crystallite sizes independent of the mean particle size. However, big particles presented bigger volumetric fraction of BCC grains. The Mossbauer spectra were fitted with a broad sextet corresponding to the ferromagnetic BCC phase, a hyperfine magnetic field distribution and a broad singlet which correspond to the ferromagnetic and paramagnetic sites of the FCC phase, respectively. Hysteresis loops showed a magnetically, soft behavior for all the samples, however, the saturation magnetization values are smaller for the original powder and for the powders wit...
Structural and Magnetic Properties of Mechanically Alloyed Fe50Co50 Systems
Acta Physica Polonica A, 2020
The nanostructured Fe-Co alloys were prepared by mechanical alloying of elemental powders using a highenergy ball mill. This made it possible to study the structural evolution of the milling product with the grinding time. In addition to previous X-ray diffraction and thermomagnetic investigations, 57 Fe based Mössbauer transmission spectroscopy was used for this purpose. Iron was alloyed with cobalt just after one hour of milling and bcc Fe-Co solid solution was formed. The analysis of the hyperfine magnetic field distribution proved that no significant structural changes occurred during further milling. A slight but regular increase in the standard deviation was observed, indicating an enhancement of topological disorder or/and an increase in internal stresses.
Journal of Metastable and Nanocrystalline Materials, 2003
Fe 50 Cu 50 solid solutions have been obtained by two different mechanical alloying routes, i.e. from Fe-Cu powders with and without premilling. These two alloying processes were studied and compared at two rotation speeds of a planetary ball-mill, namely 200 rpm and 300 rpm. The microstructural evolution of the ball-milled powders as a function of milling time was monitored using electron probe microanalysis, X-ray diffraction, scanning electron microscopy and Mössbauer spectroscopy. In both processing routes, a broad distribution of different local environments of the iron atoms was observed in the Mössbauer spectra of the fcc-FeCu phase. Mössbauer spectra show further that a fcc non magnetic Fe-rich phase is formed transiently besides the bcc-Fe phase. The Fe-Cu reactions are slowed down when premilled powders are used as starting powders but similar fcc solid solutions are formed during milling. As expected, the mechanical alloying process is faster at 300 rpm but the final results are similar using 200 rpm or 300 rpm.
Mössbauer spectroscopy study of mechanically alloyed Fe2O3–(Al, Co and WC) systems
Hyperfine Interactions, 2006
Mössbauer spectroscopy revealed that a central hyperfine interaction doublet and an additional sextet characterized the appearance of new phases in the mechanically alloyed Fe 2 O 3-Al and Fe 2 O 3-Co systems. In the Fe 2 O 3-Al system, the intensity of the central super paramagnetic doublet which represents small particles of iron, increased with increasing milling time from 5 to 30 h of mechanical alloying. The magnetic sextet characterizing hematite vanished in the room temperature Mössbauer spectra of samples produced after 25 h of mechanically alloying the 50% Fe 2 O 3 and 50% Al system. In general XRD peak broadening was observed as a result of extensive material structural distortion and formation of small particles. Fe, Al 2 O 3 and mixed iron-aluminium oxide phases were identified in the XRD patterns with a small persistence of the iron oxide up to 20 h of mechanically alloying the 1:1 system Al-Fe 2 O 3. In the 50% Co-50% Fe 2 O 3 system, a 55% abundant new phase CoFe 2 O 4 was observed, from the Mössbauer spectra of the system. The presence of this new phase was confirmed by the XRD analysis. The high energy ball milling of WC-Fe 2 O 3 revealed a more effective grinding compared to hematite alone. The hematite particles were reduced to nanosized particles.
Journal of Alloys and Compounds, 2010
The structure of annealed Sm(Co 0.6 Cu 0.4 ) 5 compounds, prepared with different Sm excess content, has been investigated by means of high resolution x-ray diffraction and scanning electron microscopy. The samples were also magnetically characterized by thermomagnetic analysis and M versus H curves at room temperature. Increasing Sm excess improves the compositional order of the 1 : 5 phase. The coercivity (H C ) and the Curie temperature (T C ) are both changed as a function of Sm excess content. The decrease in the structural defects density, resulting from the compositional order, is responsible for the observed magnetic behaviour.
Structural and magnetic properties of FeCoC system obtained by mechanical alloying
Hyperfine Interactions, 2017
Fe 96−x Co x C 4 (x = 0, 10, 20, 30, 40 at. %) alloys were obtained by mechanical alloying of Fe, C and Co powders using high-energy milling. The structural and magnetic properties of the alloy system were analyzed by X-ray diffraction, Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM) and Mössbauer Spectrometry at room temperature. The X-ray diffraction patterns showed a BCC-FeCoC structure phase for all samples, as well as a lattice parameter that slightly decreases with Co content. The saturation magnetization and coercive field were analyzed as a function of Co content. The Mössbauer spectra were fitted with a hyperfine magnetic field distribution showing the ferromagnetic behavior and the disordered character of the samples. The mean hyperfine magnetic field remained nearly constant (358 T) with Co content.