1,721,021 research outputs found
Magnetic-behavior of Fe1-xcux Powders After Milling
No full textFe1-xCux powders were ground down by ball milling. After a particular milling time, for x congruent-to 0,95, the production of fcc crystalline phase, Fe1-yCuy (y > 0,5), was evidenced by the changes in magnetic properties, X-ray and Mossbauer spectra
Iron-Alumina nanocomposites obtained by mechanosynthesis. Synthesis kinetic in a vibratory ball mill
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Structural characterization and electrochemical behaviour of Fe-Ni-Mo-B amorphous alloys
No full textA series of amorphous alloys obtained by the "melt-spinning" technique, with variable nickel and molybdenum contents, have been examined. Potentiodynamic anodic and cathodic polarization curves have been obtained for each of these amorphous alloys in various environments (1N HCl, 1N H2S04, 3% NaCl, 1N NaOH). Their electrochemical properties were correlated with the amorphous structure and with their composition, characterized by means of X-ray diffraction and Mössbauer spectroscopy. Surface morphology has been observed by Scanning Electron Microscopy (SEM). The nickel content, in amorphous Fe-Nix-Mo4-B13 (balance iron) alloys enhanced the corrosion resistance in acid (IN H2SO4, 1N HCl), neutral (3% NaCl) and alkaline (1N NaOH) environments. The molybdenum content (from 4 to 8.5%) in the amorphous Fe-Ni20-Mox-B13 (balance iron) alloys increased the corrosion resistance only in alkaline solutions. In the various environments tested, the corrosion potentials tend to ennoble on increasing ..
Further remarks on the viscosity of undercooled liquid metals and alloys: athermodynamic approach
No full textInfluence of continuous laser annealing on magnetic properties of amorphous ribbons: Connections with structural modifications and crystallization occurrence, as revealed by Mössbauer spectroscopy
No full textIn this paper the influence of continuous laser annealing on the magnetic properties and amorphous structure of Fe40Ni40P14B6 ribbons is studied; an interpretation is given relating the measured magnetic behaviour with the structural aspects revealed by Mössbauer spectroscopy. The saturation induction, the magnetostriction, the initial permeability, the constant of magnetic anisotropy and the residual stress behaviour versus the annealing temperature are reported. The experimental results show that the continuous laser irradiation can be used to improve magnetic properties under appropriate conditions. In particular the average temperature of heating must not exceed 450 K. On the other hand, we show that the effects of continuous laser annealing are pre-eminently due to both the quenching stress relaxation and the formation of crystalline phases. © 1984
Crystallization of amorphous Fe73.5Si13.5B9Nb3Cu1
No full textA study is reported on the devitrification behaviour of the amorphous alloy Fe73.5Si13.5B9Nb3Cu1. Samples of the studied glass underwent isothermal and non-isothermal heat treatments in a thermal analysis apparatus. In addition some samples were very rapidly heated to very high temperatures by means of a laser beam. In this way a large temperature range was explored and information was obtained on the overall thermal evolution of the studied amorphous alloy. The experimental results suggest that, as recently proposed in the literature, nanocrystallization can be linked to a rate limiting Nb diffusion stage in the crystal growth process. However topological short range ordering (TSRO) and chemical short range ordering (CSRO) also affect the devitrification behaviour. In the case of the studied alloy, three temperature ranges can be defined. At low temperature only TSRO occurs. Above a temperature that lies approximately in the range 450-500 degrees C, glass in glass phase separation occurs up to a temperature that lies approximately in the range 700-750 degrees C, above which it appears to be very limited. The occurrence of glass in glass phase separation appears to be necessary to obtain a fine microstructure, because Nb concentrates in the boron depleted, iron rich glassy phase. The occurrence of TSRO prior to demixing should be avoided if nanocrystallization is desired. All this appears to be satisfied by isothermally treating the sample at a temperature of 555 degrees C
Nanostructured bulk magnesium compounds for hydrogen storage
No full textThe preparation of nanostructured hydrogen storage Mg-based materials by high energy ball milling is discussed
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