Analysis of Thermal Stability of Amorphous Phases in the Al87Ni8Gd5 and Al87Ni8Y5 Metallic Alloys

Differential scanning calorimetry and X-ray diffraction analysis were used to study the kinetics of the formation of nanophase composites and the evolution of their structural parameters in the Al87Ni8Gd5 and Al87Ni8Y5 metallic glasses with different thermal stability during heating at a rate of 0.083 K/s. Using an original and a number of available models, quantitative changes in the nucleation and growth rates of Al nanocrystals and as well as the kinetic (diffusion coefficients) and thermodynamic (work for the formation of critical nuclei, difference of thermodynamic potentials of amorphous and crystalline phases, and specific free energy of nucleus/matrix phase interface) parameters were determined. A comparative analysis allowed to find that the main reason for the higher thermal stability of the Al87Ni8Y5 glass as compared to that of the Al87Ni8Gd5 glass is the lower diffusion mobility of atoms.