APFIM/TEM/SAXS studies of early stage crystallization of a Zr52.5Cu17.9Ni14.6Al10Ti5 metallic glass

The early stage of the crystallization process of a Zr52.5Cu17.9Ni14.6Al10Ti5 metallic glass has been investigated by three-dimensional atom probe (3DAP), high-resolution electron microscopy (HREM) and small angle X-ray scattering (SAXS) technique. HREM observation of the alloys annealed near Tg always showed the dispersion of nanocrystalline fcc big cube phase dispersed in the amorphous matrix whenever concentration fluctuations were detected by SAXS and 3DAP. The distribution of impurity oxygen was uniform in the amorphous state, while it was rejected from the big cube phase to the remaining amorphous phase after the primary crystallization. The time evolutions of primary crystals followed t0.5, indicating the grain growth was controlled by the volume diffusion of solute atoms.