Small-angle x-ray-scattering study of phase separation and crystallization in the bulk amorphous Mg62Cu25Y10Li3 alloy
Abstract
We report on a small-angle x-ray-scattering (SAXS) and differential scanning calorimetry study of phase separation and crystallization in rapidly quenched amorphous Mg62Cu25Y10Li3 alloy samples. Differential scanning calorimetry demonstrates the occurrence of crystallization and grain growth upon isothermal annealing of these samples at 135 °C. The SAXS studies show the presence of large inhomogeneities even in the rapidly quenched as-prepared Mg62Cu25Y10Li3 alloy that is attributed to phase separation in the undercooled liquid during the cooling process. After isothermal annealing at 135 °C for longer than 30 min the samples exhibit a strong SAXS intensity that monotonically increases with increasing annealing time. During heat treatment, crystallization and growth of a nanocrystalline bcc-Mg7Li3 phase occurs in the Y-poor and MgLi-rich domains. The initially rough boundaries of the nanocrystals become sharper with increasing annealing time. Anomalous small-angle x-ray-scattering investigations near the Cu K edge indicate that while Cu is distributed homogeneously in the as-prepared sample, a Cu composition gradient develops between the matrix and the bcc-Mg7Li3 nanocrystals in the annealed sample.
Additional Information
© 1999 The American Physical Society Received 30 November 1998 This work has benefited from the use of the beamline BL 4-2 at the Stanford Synchrotron Radiation Laboratory (SSRL), which is jointly funded by NIH and DOE. The effort of P.T. was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science, under contract No. W-31-109-ENG-38 to the University of Chicago. The financial support from the DOE (Grant No. DEFG-03-86ER-45242), from the Deutsche Forschungsgemeinschaft via Sonderforschungsbereich 345 and from NATO grant CRG.961201 is gratefully acknowledged. We thank Dr. Hiro Tsuruta, SSRL, for his assistance in the SAXS measurements. P.T. is indebted to Dr. Greg Beaucage, University of Cincinnati, for his generosity in sharing the SAXS analysis package developed on IGOR Pro platform as well as for his time.Attached Files
Published - LIUprb99.pdf
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2006-03-28Created from EPrint's datestamp field
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