Crystallization of amorphous NiZr₂

Abstract

Using a wide bandpass monochromator and a fast position-sensitive detector at the IBM-MIT beamline X20C at the National Synchrotron Light Source we have been able to perform time-resolved X-ray diffraction measurements much faster than previously possible. Using this ability we have studied the polymorphic crystallization of amorphous NiZr2. At low anneal temperatures, isothermal crystallization behavior follows closely the expected dependencies from differential scanning calorimetry measurements. At high anneal temperatures, the crystallization occurs so fast that the latent heat cannot be conducted away fast enough to maintain isothermal conditions. The temperature rise causes an increase in the rate of further crystallization. Analysis of the diffraction patterns shows that for this rapid crystallization the crystallites are initially highly deformed with the deformation annealing away with a time scale comparable with the time for crystallization. © 1988.