Primary crystallization in amorphous Al84Ni8Co4Y3Zr1 alloy

Understanding the crystallization of metallic glasses is essential for the consolidation of amorphous ribbons and powders into larger bodies. In this paper, we describe the evolution of crystalline phases formed during thermal induced crystallization of amorphous Al 84 Ni 8 Co 4 Y 3 Zr melt-spun ribbons. Partially and fully crystallized samples were prepared either by heating in a differential scanning calorimeter to temperatures corresponding to each crystallization stage or by isothermal annealing in a heated oil bath at 473 and 628 K (±1 K). Isothermal annealing time ranged from 1 to 120 min. Thermal analysis. X-ray diffraction and transmission electron microscopy were used to determine both the reactions involved and the phases formed upon crystallization. Crystallization occurred in multiple stages, with nanometer-sized crystals of fcc-Al and Al 9 Co 2 phases formed in the first and second initial stages, respectively, and formation of Al 16 Ni 3 Y-like. Al 3 Y and Al 3 Zr phases upon the final reactions. Both fcc-Al and Al 9 Co 2 were found to primarily crystallize from the amorphous material. An Al 16 Ni 3 Y-like phase was formed by polymorphous crystallization of the amorphous phase remaining after the second stage.