Analysis of Al nanocrystals nucleation process in AlNiGd metallic glass during annealing and severe plastic deformation

Analysis of the process of nanocomposite structures formation in Al$_{87}$Ni$_8$Gd$_5$ metallic glass under isothermal annealing at 448 K and under high pressure torsion straining was performed in the frames of the classical equation for rate of homogeneous nucleation. The value of specific free energy of the nucleus/matrix interface, which agreed with the experimentally established volume density of nanocrystals, was used as the only one free parameter. The nucleation rate during annealing was estimated using the effective diffusion coefficient, which was taken from the literature, while in the equation for deformation-induced nucleation rate the value of the diffusion coefficient determined by the size of nanocrystals in the deformed sample was used. It was established that approach proposed in this work, which consisted in substituting into the equation for nucleation rate during deformation the value of the work of critical nucleus formation corresponding to room temperature, correctly described the experimentally established enhanced volume density of nanocrystals in deformed samples.