Influence of the heat treatment on the crystallization mechanisms of Al85Y5Ni8Co2 metallic glass

Glass forming ability, crystallization and stability of a rapidly quenched, Al85Y5Ni8Co2 amorphous alloy have been investigated by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Calorimetric results obtained in continuous heating regime reveal a glass transition followed by a wide supercooled liquid region (27 °C) and then by a three-stage crystallization process, starting with the primary formation of nanoscale α-Al particles. However, isothermal annealing of the as-quenched samples below the glass-transition temperature activates the first two crystallization stages and an unidentified compound is formed conjointly with α-Al. Kinetic analysis suggests that crystallization occurs through nucleation and three-dimensional growth.