Crystallization kinetics of Al86Ni8Ho6 amorphous alloy

Abstract

Abstract⎯We investigate the processes of crystallization and determined the structure and thermal properties of Al 86 Ni 8 Ho 6 amorphous alloy in a wide temperature range. A three-stage nature of the crystallization process upon heating to a temperature of 700 K is found. According to data of high-temperature X-ray diffraction analysis, the crystallization of an Al 86 Ni 8 Ho 6 amorphous ribbon is rather complex: aluminum crystallites grow in the amorphous phase to a temperature of 470 K, a Ho 3 Ni 5 Al 19 phase is formed above 563 K, and a HoAl 3 phase appears above 598 K. The phases of Ho 3 Ni 5 Al 19 and HoAl 3 are retained up to a temperature of 723 K. A three-stage kinetic model of the crystallization process with the reaction sequence is proposed based on calculations by multivariate nonlinear regression. The values of the total activation energy for each crystallization stage reach 239, 378, and 247 kJ/mol.