STUDYING CRYSTALLIZATION OF AMORPHOUS METAL-ALLOYS BY TIME-RESOLVED EXAFS

The first complete observation of a temperature-induced crystallizatio n process using time-resolved X-ray absorption spectroscopy (XAS) is p resented. The sub-T(g) reordering of a Ni60B40 amorphous alloy has bee n investigated, yielding a complete characterization from both the str uctural and kinetical points of view. This enabled the sharpening and shift of the Ni-Ni radial distribution function during the annealing t o be quantified and the type of crystallization process to be determin ed; it was found to be an interface-governed growth of pre-existing nu clei. Theoretical estimates of the parameters of the crystallization k inetics confirm this interpretation of the data.