Thermal Cycling and Amorphous-Cyrstalline Transition in the Amorphous C60-Zr40 Alloy System

Abstract

ABSTRACTThe transition behavior of the amorphous Cu60Zr40 alloy system during its transition to crystallinity by thermal cycling has been studied. A Differential Scanning Calorimeter (Perkin-Elmer model DSC-2) was used to record, in situ, the onset of thermal evolution of the sample during the course of transition. Analysis of DSC tracings reveal that: a. Transition occurs at a lower temperature than those transformed without thermal cycling, b. The amplitude of the exothermic rise decreases proportionally with increasing numbers of the thermal cycles and c. Details of the profile of the DSC tracing, i.e., the width of the exothermic rise and the presence of the secondary exotherm, are quite different from those transformed without thermal cycling. Preliminary high resolution electron microscopy of thermally cycled samples indicate random distribution of copper-rich precipitates at the early stages of cycling and their coalescence during the final stage of crystallization. For large number of cycles, however, the induced strains from thermal cycles contributes to the image contrast of the quenched solid thus allowing the assessment of the proposed atomic level stresses and strains, via technique of high resolution electron microscopy.