CONSECUTIVE NUCLEATION EVENTS DURING DIVETRIFICATION OF Zr52.5Cu17.9Ni14.6Al10Ti5 BULK METALLIC GLASS

Abstract

Differential scanning calorimetry, x-ray, and in-situ synchrotron diffraction were used to study the divitrification of Zr52.5Cu17.9Ni14.6Al10Ti5 bulk metallic glass. Two consecutive exothermal peaks were identified by differential scanning calorimetry during both isochronal and isothermal scans. Examination of the X-ray and in-situ synchrotron diffraction patterns at various stages of annealing confirms that the exothermal peaks correspond to two nucleation events, with different local atomic structures. Modeling of the calorimetry data indicates that the devitrification in this alloy is adequately described by Johnson�CMehl�CAvrami theory with a two-step consecutive reaction model.