NANOCRYSTALLIZATION OF CO33ZR67 GLASSES

Crystallization of Co33Zr67 glasses was studied at temperatures below and above the glass transition temperature, T-g, by means of TEM and d ifferential scanning calorimetry (DSC). Nanocrystalline cubic structur e (''big'' cubes; a = 1.22 nm) was revealed at temperatures above T-g as well as at low annealing temperatures in DSC. Systematic analysis o f the overall transformation kinetics of the amorphous-to-nanocrystall ine reaction leads to the conclusion that primary crystallization with time-dependent growth rates instead of polymorphic transformation, ta kes place. We propose that the formation of this nanostructure is prov oked by oxygen contamination in the glass.