Neutron and X-Ray Scattering For Dynamic Study of Bulk Metallic Glasses

L. Yang Department of Chemical and Materials Engineering, University of Cincinnati

A comprehensive report on the study of the devitrification of bulk metallic glasses (BMGs) by both ex-situ and in-situ experiments is given. Three types of BMGs have been studied, including Zr52.5Cu17.9Ni14.6Al10Ti5, Mg65Cu25Tb10 and Zr50Cu40Al10, standing for Zr-based good glass former, Mg-RE-based glass, and marginal glass respectively. The ex-situ experiments include DSC, XRD, TEM and Atom Probe. The in-situ experiments include simultaneous small-angle X-Ray scattering (SAXS) and wide-angle X-Ray scattering (WAXS), and total scattering by both neutron and synchrotron X-Ray scattering. Data analysis, including the kinetic model of DSC traces, the refinement of the interference peaks on SAXS patterns, structure identification for products of different transformation stages on WAXS patterns, evolution of short range order (SRO) into medium range order (MRO) on the pair distribution functions (PDFs), have been attempted. Combination of all experimental results indicates that the intermediate nanoclusters play an important role in the early stages of devitrification, and the non-periodic atomic packing is characteristic for good glass formers.

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