The relation between the bulk and ribbon Zr55Ni25Al20 metallic glasses

The planar-flow-casting technique and quenching in flowing water were used to produce the glassy Zr55Ni25Al20 ribbon and bulk samples. The thermodynamic states of these two types of samples were compared using differential scanning calorimetry and analysis of the structural relaxation kinetics. The relaxation enthalpy is 3 times larger and the glass transition temperature is higher by 67.5 K in the case of the ribbon sample. These differences were theoretically confirmed by a kinetic model and were caused by the different quenching rates for the ribbon and bulk samples, namely 105 and 102 K s-1, respectively. X-ray analysis has shown, that the main difference between the studied glassy structures consists in the different degree of the short-range order in the samples. (orig.)