In-situ neutron scattering study of crystallization in a Zr-based bulk metallic glass

Crystallization of a Zr-based bulk metallic glass (Zr50.4Cu40.6Al9) upon isothermal annealing has been investigated using in-situ neutron diffraction and the pair distribution function (PDF) method. By extracting the contribution of the crystalline phase from the total scattering, we are able to obtain the real-time structure factor and pair distribution function for the crystalline phase as well as its volume fraction. Our analysis shows that the crystallization follows the Johnson-Mehl-Avrami law with a time exponent of 4.0 +/- 0.2, indicating a three-dimensional nucleation and growth process. The analysis method established in the present study paves a new way for probing the kinetics of phase transformation for a broad range of non-crystalline materials including liquids and glasses.