Maksymov V. Kinetics and mechanisms of high-strength nanostructured states formation in amorphous alloys based on aluminum

The object is the nonequilibrium diffusion-controlled crystallization of the amorphous phase as the process of formation of nanocomposite structural states. The aim is to establish the mechanisms of the formation of high-strength nanocomposite structural states in amorphous Al-based alloys and the factors that determine the thermal stability of metallic glasses with nanocrystal forming ability. The methods of investigations are X-ray analysis, transmission electron microscopy, electrical resistance and microhardness measurements, differential scanning calorimetry. The eutectic colonies in the two-phase nanocomposite structure in the Al86Ni2Co5.8Gd5.7Si0.5 alloy were firstly observed in Al-based glasses and the process kinetics was described within the classical Kolmogorov's model under assumption of the real transformed volumes summation. The temperature dependencies of the effective diffusion coefficients which govern the growth of nanocrystals have been established and it has been shown that this parameter determines thermal stability of nanocrystal forming amorphous alloys. The analytic models which describe isothermal nanocrystallization kinetics and growth of nanocrystals under non-isothermal conditions were developed. It has been found for the first time that preliminary heating of the Al87Ni8Y5 samples results in enhancement of nanocomposite structure microhardness. Scope: scientific research, production of amorphous alloys, educational process.