Phases formed during crystallization of Zr55Al10Ni5Cu30 metallic glass containing oxygen

In the present work the Zr55Al10Ni5Cu30 alloy has been processed by melt spinning and die-casting into a chilled copper mold. The ribbon was fully amorphous (X-ray diffraction and transmission electron microscopy) and cast samples partially crystalline. The amorphous ribbon was crystallized and analyzed by differential scanning calorimetry, X-ray diffractometry and transmission electron microscopy. The smaller supercooled liquid range of the glassy ribbons (60 K) and partial crystallization of a larger cast sample during quenching indicate the presence of oxygen in both samples (similar to0.8 at.%). Although the crystallization process of the glassy ribbon, a glass transition followed by a single crystallization peak, showed the same crystallization process as reported by the literature, the heat release and the phases formed differed. The main phases formed were Zr2Cu, a complex 'big-cube' fcc Zr4Cu2O-type phase and a tetragonal phase, not reported before to our knowledge, containing a lattice parameter of 2.8 nm. (C) 2002 Elsevier Science B.V. All rights reserved.