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The work is aimed at the development of a new sintered aluminium alloy with a low temperature coefficient of linear expansion that opens fundamentally new opportunities for solving the modern needs of domestic machinebuilding and instrument-making enterprises in light materials with special physical properties. Phase composition, structure and properties of cast aluminium alloys Al-Si-Ni with different contents of silicon and nickel, as well as powders obtained by grinding rapidly-quenched metal ribbons of these alloys in a high-energy ball mill are studied using various methods of structural analysis. The obtained values of the coefficient of linear expansion of the studied alloys in the cast state are significantly lower than those of pure aluminium, and they amount to = (11-15) 10-6 K-1. The method of obtaining a powder of a rapidly-crystallized alloy by manufacturing a rapidly-quenched metal ribbons using melt spinning followed by its dispersion in a high-energy ball mill is proposed for the fabrication of finely-dispersed powder and subse- quent hot pressing. [ABSTRACT FROM AUTHOR]

By the method of cyclic voltammetry, we study the corrosion resistance of amorphous and crystalline Al87Ni8Y5 alloys in a 0.5 M aqueous NaCl solution for different sweep rates of potential of the electrode surface (10, 20, 50, and 100 mV/sec). We find the electrochemical characteristics of crystalline Al, Ni, and Y in solutions of sodium chloride. The diffusion coefficients of Al3+ and Ni2+ ions are determined. It is shown that the alloys are ionized in this solution in three stages and the diffusion rate of Al3+ from the near-electrode layer is lower than for Ni2+ ions. [ABSTRACT FROM AUTHOR]

We estimate the electrochemical activity of specimens of the amorphous metallic alloys (АМA) AlNiY, AlNiYGd, and AlNiDyY in alkaline solutions of potassium hydroxide of different concentrations and the influence of partial substitution of 1 at. % Gd or Dy for Y. It is shown that all investigated specimens are corrosion-resistant in the course of cyclic polarization within the potential range from - 1.2 to + 1.0 V in aqueous KОН solutions of various concentrations (0.5-5.0) М. It is shown that AMA electrodes alloyed with 1 at.% Dy exhibit the highest catalytic activity in a 4 М KОН solution. [ABSTRACT FROM AUTHOR]

Decomposition of supersaturated solid solution of aluminium alloys alloyed with Sc and Zr have been studied in the work. The binary hypereutectic Al-Sc alloys, hyperperitectic Al-Zr alloys and ternary Al-Sc-Zr alloys were chosen. Alloys were obtained by the melt-spinning. Melts were quenched from temperatures of T = 1000 °C and T = 1400 °C. The crystallization of anomalously supersaturated solid solution (Tquen: = 1400 °C) or the crystallization with the formation of -fan- structure (Tquen: = 1000 °C) are possible. The decomposition of anomalously supersaturated solid solution is continuous, with the precipitation of nanosized spherical Al3X (X = Sc, Zr) particles. The loss of thermal stability of Al-Sc alloys is due to the loss of coherence of the strengthening Al3Sc phase. In Al-Zr alloys the loss of strength is due to the formation of a stable tetragonal DO23-ordered Al3Zr phase. After co-alloying of Al by Sc and Zr a bimodal grained structure was observed for the hypereutectic ternary alloy (Tquen: = 1400 °C). Nanosized grains of 50-60 nm were present on the boundaries of 1-2 μm large-sized grains. Transmission electron microscopy shows the formation of nanocomposite Al3Zr/Al3Sc particles. The formation of Al3Zr shell changes the nature of the interfacial fit of the particle with the matrix and slows down the decomposition during the coalescence. [ABSTRACT FROM AUTHOR]

Structural changes of rapidly cooled ribbons of the amorphous alloys Al(Ni,Co,Fe)(Y,Gd,Nd,La), which occur during heating at a rate of 10 K/min and lead to a loss of ductility, have been investigated experimentally. It has been shown that samples of the studied alloys are divided into two groups, in the first of which the loss of ductility is due to the formation of a nanocomposite structure, whereas the embrittlement of samples in the second group is caused by processes of structural relaxation in the amorphous phase (decrease in the concentration of a free volume). It has been established for the first time that there is an empirical correlation between the dynamic temperature, after heating to which the alloys lose their ductility at room temperature, and the ratio of the shear modulus to the elastic modulus of the alloys, which is calculated from the nominal chemical composition. [ABSTRACT FROM AUTHOR]