Corrosive properties of some Al-based amorphous metallic alloys (AMA) and the relationship between the AMA composition and nature of protective layers on the surface of alloys were studied. The complex of physico-chemical methods, namely the potentiometry, voltammetry, electrochemical impedance spectroscopy and electronic microscopy, has been used. It was shown that the influence of Dy doping on the same characteristics of alloys is opposite to that of Gd. It increases corrosion resistance of Dy-containing alloys in comparison to the reference Al87Y5Ni8 alloy. Partial substitution of 4 at. % Ni by Fe causes further increase of corrosion resistance of Al87Gd5Ni4Fe4.http://iopsciencep.org/article/10.1088/1742-6596/289/1/012019.io

The effect of Ni and Mo alloying additions on crystallization of an Fe–Si–B based amorphous alloy was studied by applying various experimental techniques – DSC, XRD and TEM. It was shown that both alloying additions Ni and Mo change the crystallization temperature as well as the activation energy of primary crystallization. The phases formed during primary crystallization for the Fe80Si6B14 and Fe78.5Ni1Mo0.5Si6B14 alloys were the same, however the morphologies were significantly different. The addition of 1.0at.% of Ni and 0.5at.% Mo changed the crystallization mechanism and the type of formed phases. Such additions also resulted in formation of nanocrystals. The kinetic and thermodynamic characteristics of annealed specimens of amorphous metallic Fe80Si6B14 and Fe78.5Ni1Mo0.5Si6B14 alloys were established. These characteristics were determined based on measurements of instantaneous changes of electrical strength. It was shown that the method of electromotive force measurements was more sensitive to structural changes and the phase composition of amorphous metallic electrodes in comparison with the X-ray method.

The annealing of amorphous alloys, that is needed in order to improve their properties, is connected with various changes of structure and properties. The understanding of such changes is interesting both from fundamental and applied views. On that reason the influence of Mo and Cr admixtures on the main structure parameters and physical and chemical properties has been studied. For investigation of amorphous alloys the X-ray-diffraction, differential scanning calorimetry, magnetic susceptibility and High-resolution microscopy methods were used. Experimental data allowed us to estimate the changes in crystallization kinetics and to calculate the activation energies. These results were analyzed conjointly with data on X-ray diffraction and magnetic measurements.

The influence of the formation of intermetallic compounds on the electrochemical properties of anAl 87 Y 5 Ni 8 amorphous metallic alloy (AMA) was investigated by means of differential scanning calorimetry (DSC), X-ray diffraction (XRD) and high-resolution electron microscopy (HREM).It is shown that the crystallization process taking place upon annealing can be subdivided into three stages corresponding to DSC maxima at 505, 602 and 632 K, respectively.The first and the second stage of crystallization were attributed to the formation of an fcc-Al(Y) solid solution in the amorphous matrix.During the third stage of crystallization precipitation of the fcc-Al(Y) solid solution and of the ternary compound Al 19 Y 3 Ni 5 with orthorhombic Al 19 Gd 3 Ni 5type structure was observed.An increase of the size of the precipitated phases reduces the corrosion rate coefficient b of the AMA.Amorphous metallic alloy / Crystallization process / Corrosion resistance

Crystallization of amorphous Al-based alloys (Al–Y–Gd–Ni–Fe) was investigated by applying differential scanning calorimetry (DSC), X-ray diffraction (XRD) and high resolution electron microscopy (HREM). It was shown that the crystallization in the examined alloys proceeds in three stages (DSC maxima). The two first stages are attributed to formation of solid solution of fcc Al(RE) nanograins in amorphous matrix. In the third stage the precipitation of ternary compound Al19Ni5RE3 of the orthorhombic Al19Ni5Gd3-type structure was observed. A partial substitution of Ni by Fe causes a change of stoichiometry and crystal structure of the ternary compounds: Al8TM4RE (TM=Fe, Ni; RE=Y, Gd) of the tetragonal ThMn12 (Al8Mn4Ce)-type structure. A partial replacing of Y atoms by Gd in the Al87Y5Ni8 based alloy shifts the Al(RE) nanocrystallization to lower temperatures. In contrast to this a partial replacing of Ni by Fe shifts the nanocrystallization to higher temperatures.

A procedure of thermal heating of amorphous metallic alloys (AMA) is extensively used to obtain nanocrystals. In this case, the information about structural changes in the process of growth of nanocrystals is very important, especially for a group of Fe-based AMA for which soft magnetic properties can be improved by applying a well-defined procedure of thermal annealing. This improvement is usually explained by the formation of a nanocrystalline phase in the amorphous matrix or by changing the effective magnetostriction constants [1, 2]. On the other hand, it is also of importance to study the influence of dopants on the kinetics of crystallization. Copper and niobium are the most effective of them [3-5]. The structural changes caused by the addition of these metals promote the changes in the main physicochemical properties and, in particular, in the magnetic properties [6, 7].

Formation of nanostructured functional coatings from water solutions of carbon-chain oligoperoxide surfactants (OPS) composed of vinyl acetate (VA), 2-tert-butylperoxy-2-methyl-5-hexen-3-yne (VEP), maleic anhydride (MA) and oligoperoxide metal complexes of (OMC) with different contents of coordinated Cu2+ and Fe3+ cations on the Fe78.5Ni1.0Mo0.5Si6.0B14.0 and Fe73.1Cu1.0Nb3.0Si15.5B7.4 amorphous alloys(AMA) has been studied. The existence of several stages of the coating formation depending on oligoperoxide nature and the solution concentration has been established. The nature and concentration of oligoperoxides define the structure and packing density of oligomer molecules in the adsorption layers. The oligomer films coordinated by Cu2+ on the Fe78.5Ni1.0Mo0.5Si6.0B14.0 and Fe73.1Cu1.0Nb3.0Si15.5B7.4 AMA are more rigid.

The passivation layers on the Co-Fe-Si-B-M amorphous metallic alloys (AMA) surface were synthesized at 64 h contact with 3% NaCl aqueous solution. Potentiometric method was applied to study the dynamics of the passivation of the AMA surface. Electrochemically synthesized oxide-hydroxide passivation films have been studied by X-ray diffraction (XRD) analysis, X-ray microprobe analysis, scanning electron microscopy (SEM), voltammetry and electrochemical impedance spectroscopy (EIS) methods. It was shown that simultaneous presence of Cr, Mn, Ni and Mo as doping elements M makes the quality of the passivation layers worse changing the surface morphology and electrochemical characteristics.

The structure of amorphous Fe-Si-B alloy doped with Ni, Mo, Nb and Cu has been studied by X-ray diffraction method. It is shown that annealing of all samples leads to the formation of intermediate short range order which disappears before crystallisation. The structure parameters show the influence of doping atoms on atomic arrangement.

The structures of the amorphous alloys Co67.2Fe3.8Cr3.0Si14.0B12.0 and Co66.5Fe4.0Mo1.5Si16.0B12.0 have been studied by means of X-ray scattering at different temperatures. It is shown that the amorphous structure is thermally stable up to 673K. Upon initial crystallization the formation of a β-Co- and a Co3B-based phase is observed. With further heating (Co3B) disappears and the formation of (Co2Si) and (Co2B) completes the process.

Changes of the compositional and topological arrangement of the atoms during annealing of Fe–Si–B–(Me) amorphous alloys ribbons, changes of structure, magnetization and electrochemical parameters of dissolving were investigated. X-ray powder diffraction analysis of amorphous metallic alloy samples annealed at 873K showed that the stability of the Fe3B-phase increases with increasing Ni content. The results obtained by the voltammetric method, not only correlate with the results of magnetic and X-ray diffraction studies, but also provide information on surface redox processes.