Estimation of diffusivity governing primary nanocrystallisation and its relation to thermal stability of amorphous phases |
| |
Authors: | VI Tkatch SG Rassolov VK Nosenko VV Maksimov TN Moiseeva KA Svyrydova |
| |
Institution: | 1. A.A. Galkin Donetsk Institute for Physics & Engineering of NAS of Ukraine, 72 R. Luxemburg Str., 83114, Donetsk, Ukraine;2. G.V. Kurdymov Institute for Metal Physics of the NAS of Ukraine, 36 Vernadsky St., Kyiv, 03142, Ukraine |
| |
Abstract: | Thermal stability and changes of both the average size of Al nanocrystals and their crystallised volume fraction formed in a series of the amorphous Al–(Ni,Co,Fe)–(Gd,Y,Tb) alloys as well as of α-Fe(Si) in the Fe73.5Si13.5B9Cu1Nb3 alloy under isothermal conditions have been experimentally studied by a combination of X-ray diffraction (XRD) analysis, differential scanning calorimetry (DSC) and electrical resistance measurements. The experimental data have been fitted with the analytical models describing the diffusion-limited growth of nanocrystals and nanocrystallisation kinetics accounting for impingement of diffusion fields and the values of the effective diffusivity governing this process have been estimated. The obtained values of the diffusivity in Al-based amorphous alloys follow the Arrhenius-type dependencies with correlation between the pre-exponential factors and the activation energies somewhat different from that found for impurity diffusion coefficients in amorphous alloys. It has been established that at the onset crystallisation temperatures varying from 453 to 778 K, the values of the effective diffusivity in the investigated amorphous alloys are in the narrow range of 1.7–4.7 × 10? 20 m2 s? 1, which indicates a crucial role of the effective diffusivity for the thermal stability of nanocrystals forming amorphous alloys and the possible reason for this is discussed. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|