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Mechanical alloying technique is used for the decrystallization of Fe100-xBx samples with soft magnetic character. Wide angle X-ray scattering (WAXS) and differential scanning calorimetry have been used to monitor the decrystallization kinetics, whose time dependence can be fitted by a stretched exponential function. In all the samples, milling times of around 500 h lead to very low crystallinity percentages (around 5%). This residual crystalline phase corresponds to a mixture of FeB and Fe2B phases, and the α-Fe phase almost disappeared at the same time. During the decrystallization, the grain size of the α-Fe phase changes appreciably from 40 down to 15 nm. Magnetic properties of the samples in their final lowest crystalline state showed different behaviours for the samples rich in boron or in iron. [Copyright &y& Elsevier]

The microstructural characteristics of glass coated microwires, Fe75.5B13Si11Mo0.5, are studied by wide angle X-ray scattering (WAXS) considering their geometry determined by their fabrication. The raw WAXS data show three wide diffraction peaks corresponding to different structural correlations, whose first and second ones correspond to long correlation distances in the Pyrex layer (≈3.5 Å) and in the metallic core (≈2.0 Å). The high q width peak (≈1.5 Å) seems to be formed by an overlapping of two peaks associated to short correlation distances in the layer and in the core. The diffraction patterns normalized to absolute units show that the higher the ρ ratio the higher the intensity of the core peaks and the lower the intensity of the layer peaks. From the peaks corresponding to the metallic core, we can deduce small (although systematic) changes of the short-range order in the glassy metallic core of the microwires. [Copyright &y& Elsevier]

Abstract: Magnetic, transport and structural properties of granular Cox–Cu100−x (510 partial evidences of granular structure have been observed. For x≥30 anisotropic contribution to GMR has been observed giving rise to non-monotonic dependence of GMR on the field. Temperature dependence of magnetization measured during a cooling regime without external magnetic field and in the presence of the field shows considerable difference at low temperatures, being attributed to the presence of small Co grains embedded in the Cu matrix. By X-ray diffraction we found, that the structure of the metallic nucleus is granular consisting of two phases: fcc Cu appearing in all the samples and fcc α-Co presented only in microwires with higher Co content. For low Co content (x≤10%) X-ray diffraction technique indicates that Co atoms are distributed within the Cu crystals. The quantity and the crystallite size of the formed phases strongly depend on the geometry of the microwire. The structure, magnetic and transport properties were affected by the glass coating inducing the internal stresses and affecting the quenching rate. [Copyright &y& Elsevier]

Abstract: Direct Alcohol Fuel Cells (DAFC) are considered an attractive option to the utilization of fossil fuels. At the same time, the growing impulse in the promotion of the use of energy from renewable sources is gaining a most important role. Platinum is regarded as one of the best catalysts but its cost is high and it shows susceptibility towards CO poisoning. These problems can be minimized using cocatalysts. In this work, ethanol and bioethanol electro-oxidation has been studied using two amorphous tricatalytic alloys: Ni59Nb40Pt0.6Sn0.2X0.2 (X = Pd, Co) as anodes. Tolerance to CO has also been studied. Alloys were prepared by mechanical alloying and characterized by several techniques such as DSC, XRD and SEM. The results show that amorphous catalysts are effective for ethanol as well as for bioethanol electro-oxidation. When comparing the effect of cobalt and tin as cocatalysts, the tests show that cobalt leads to a higher catalytic activity. [Copyright &y& Elsevier]

Abstract: We report on fabrication, structural and magnetic characterization of Cu70(Co70Fe5Si10B15)30 microwires with total diameter of 28.2μm and metallic nucleus diameter of 15.2μm produced by the Taylor-Ulitovski method containing 30% of alloy composition commonly used amorphous soft magnetic material and 70% Cu. The structure consists of crystalline Cu, and mixture of ferromagnetic phases. The as-prepared Cu70(Co70Fe5Si10B15)30 microwires present coercivity of about 85Oe at room temperature. Temperature dependence of coercivity is measured. Significant increase of coercivity till 135Oe is observed at about 50K. Magnetization measured under applied magnetic field (FC) and without magnetic field (ZFC) exhibit significant difference attributed to the inhomogeneity of as-prepared samples consisting of crystalline paramagnetic Cu matrix with ferromagnetic entities. MR related with existence of ferromagnetic grains in paramagnetic Cu matrix has been observed. This MR increases with decreasing temperature (up to 1.6% at 5K). [Copyright &y& Elsevier]

Abstract: Different kinds of magnetic anisotropies have been induced during the nanocrystallization process of Co- and Ni-rich amorphous ferromagnetic (Finemet) ribbons using diverse procedures like the application of a constant stress or an axial magnetic field during the annealing process. Magnetization measurements have evidenced the anisotropy of the treated samples. The main goal of this work has been the structural and microstructural analysis of the treated ribbons using X-ray Diffraction (XRD) and Atomic Force Microscopy (AFM), detecting substantial differences in the crystallization state and grain size of the samples depending on the treatment that was carried out. Moreover, AFM measurements revealed in all the treated samples a strong nanocrystallization of the surface without evidences of amorphous matrix, which contrast with XRD measurements that have shown a high content of amorphous phase in the bulk of the ribbons. Magneto-optical Kerr effect measurements have been performed with the aim to elucidate the complex magnetic behavior that is expected for the surface of the ribbons, measuring surface hysteresis loops that show much higher coercive field values than in the bulk. [Copyright &y& Elsevier]

Disordered Fe70Al30 alloy was measured versus annealing temperature by X-ray diffraction, differential thermal calorimeter, magnetization and Mo¨ssbauer spectroscopy. All of them show a critical behaviour around 475 K. The critical behaviour is related to an ordering of the alloy that happens at that temperature linked to a decrease of the magnetic properties of the sample. [Copyright &y& Elsevier]

Abstract: Cu80Co19Ni1 glass covered microwire samples with different geometric ratio, 0.13⩽ρ⩽0.5, has been investigated by using X-ray diffraction (XRD) and VSM technique. Our results show (i) the presence of FCC Co crystallites dispersed on the Cu matrix, (ii) the observation in all the samples of the coercivity, at room temperature, of the order of kA, exhibiting a maximum and decreased down to a value of the order of the room temperature one at 25K. These results are discussed in terms of a distribution of superparamagnetic Co nanoparticles. [Copyright &y& Elsevier]