Crystallization Kinetics Study in Al۸۷Ni۱۰La۳ Amorphous Alloy

In this study, the crystallization behavior of melt-spun Al۸۷Ni۱۰La۳ amorphous phase was investigated by using X-ray diffraction and non-isothermal differential thermal analysis techniques. The results demonstrated that the amorphous phase exhibited two-stage crystallization on heating, i.e., at first step the amorphous phase transforms into α-Al phase and at second step Al۱۱La۳ and Al۳Ni intermetallic phases precipitate, simultaneously. The activation energies of the crystallizations of the amorphous phase were evaluated by the Kissinger equation using the peak temperature of the exothermic reactions. The values of two-step crystallization activation energies were approximately ۱۷۳.۷±۶ and ۲۷۸.۴±۵ kJ/mol, respectively. The Avrami index was calculated for the first and second step of crystallizations and obtained ۰.۹ and ۳.۸ respectively. This kinetics investigation indicated that in the first step of crystallization of Al۸۷Ni۱۰La۳ alloy, the nucleation rate decreases with time, and the crystallization is governed by a three-dimensional diffusion-controlled growth, while the second stage was in interface control regime.

Keywords:

Amorphous alloy , Rapid solidification , Crystallization , Thermal analysis