Complex crystallization mode of amorphous/nanocrystalline composite Al86Ni2Co5.8Gd5.7Si0.5

Kinetics of the first crystallization stage of Al86Ni2Co5.8Gd5.7Si0.5 amorphous alloy and structure of the partially crystallized specimens were investigated by measurements of electrical resistance, X-ray diffraction and transmission electron microscopy. The presence of Al nanocrystals and eutectic colonies consisted of mutually oriented crystals of Al and metastable phase was found. The transient nucleation and slowing-down diffusion-limited growth and the interface-controlled growth of the quenched-in nuclei were identified as mechanisms of formation of the Al nanocrystals and eutectic colonies, respectively.

Research Highlights
► Al86Ni2Co5.8Gd5.7Si0.5 amorphous alloy crystallizes via complex mode.
► The partially crystallized structure consists of Al nanocrystals and eutectic colonies.
► The (primary + eutectic) crystallization kinetics has been analytically described.