Abstract
Differential scanning calorimeter (DSC) has been used to study the crystallization kinetics of Al87.5Ni7Mm5Fe0.5 alloy. Both isochronal and isothermal DSC plots showed that the Al87.5Ni7Mm5Fe0.5 alloy undergoes three stages crystallization process. The first peak corresponds to the precipitation of fcc-Al from the amorphous matrix at around 160°C. Isothermal DSC traces showed that there is a short incubation stage for the formation of nanoscale Al particles. The value of Avrami exponent suggests that the crystallization of Al crystals starts with a nucleation process for a short time and finally controlled by a growth mechanism. The second peak corresponds to the crystallization of Al11(La,Ce)3 from the matrix at around 320°C with a nucleation rate, which decreases with time, and a constant growth rate. The activation energy calculated for the crystallization of Al11(La,Ce)3 phase is 288±5.9 kJ/mol, 324.6±18 kJ/mol, 292±6 kJ/mol by Kissinger, Johnson-Mehl-Avrami and Arrhenius type equations. The difference in the values of kinetic energy is mainly due to different annealing conditions. The third peak at around 340°C corresponds to the precipitation of intermetallic compounds from the remaining matrix.
