Structure and crystallization kinetics of amorphous Al-Ni-Si alloy

In the present work, the structure and crystallization kinetics of rapidly solidified Al(70)Ni(13)Si(17) amorphous alloy have been investigated by a combination of differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). Amorphous ribbons were obtained by melt spinning at wheel speeds higher than 10 m/s. Crystallization of amorphous Al(70)Ni(13)Si(17) alloy during continuous heating in DSC, takes places in three stages: (1) formation of fcc-Al and hexagonal phases; (2) growth of fcc-Al and hexagonal phases; (3) formation of fcc-Si and orthorhombic Al(3)Ni phases. Isothermal annealing DSC traces for this amorphous alloy, the first crystallization peak showed a clear incubation period, and the Avrami time exponent n has been determined to be 2.4-2.8 using the Johnson-Melh- Avrami analysis. This suggested that the transformation reaction involved continuous nucleation and three dimensional diffusion-controlled growth. Electrical resistivity of the alloy was measured as 33 x 10(-6) Omega.cm for the amorphous structure and 1 x 10(-6) Omega.cm for the crystalline one. This study describes the structure and crystallization kinetics of a rapidly solidified Al(70)Ni(13)Si(17) amorphous alloy.