Grain size estimations from the direct measurement of nucleation and growth

Microstructures that emerge during the crystallization of amorphous materials depend on nucleation and growth kinetics. The ability to predict these final microstructures, particularly the average grain size, would allow better control of material properties. Well-established crystallization theories have proposed mathematical models to describe these microstructures. What remains missing, however, is an independent experimental verification of the microstructures these models predict. Here, we report in situ transmission-electron-microscopy experimental methods that assess independently the nucleation and growth rates of crystallizing grains. A consequence of having a separate, experimentally-determined description of nucleation and growth is the ability to predict the average grain size over a broad range of temperatures. The results from these experimental methods verify the theoretical models that were posed several decades ago. (c) 2005 American Institute of Physics.