Nanoscale phase separation in metallic glasses studied by advanced electron microscopy techniques

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • Y. Hirotsu
  • T. Hanada
  • T. Ohkubo
  • A. Makino
  • Y. Yoshizawa

Detail(s)

Original languageEnglish
Pages (from-to)1081-1088
Journal / PublicationIntermetallics
Volume12
Issue number10-11 SPEC. ISS.
Publication statusPublished - Oct 2004
Externally publishedYes

Abstract

To understand atomic structures of metallic glasses, advanced electron microscopy was employed to analyze local structures of some Fe-based and Zr-based metallic glasses. In the as-formed Fe70Nb10B 20 and Fe73.5Nb3Si13.5Cu 1B9 glasses, crystalline nano-clusters as small as 1 nm were observed using HREM (high resolution electron microscopy) under optimized defocus conditions. Nano-diffraction with a probe size of 1 nm revealed diffraction patterns of bcc-Fe and Fe-compound, suggesting the presence of nanoscale phase separation in these as-formed specimens. Atomic pair distribution function was calculated from analyzing electron diffraction intensity obtained from a large area in the samples using energy-filtering. For the Fe-Nb-B glass, an averaged atomic structural model with 2500 atoms was constructed using reverse Monte-Carlo calculation followed by Voronoi polyhedral analysis. The analysis revealed the presence of bcc-Fe-like, B-centered trigonal prism and highly coordinated Nb-Fe polyhedral structures, which was consistent with experimental results of HREM and nano-diffraction. A Zr 71Cu13Ni10Ti3Al3 bulk metallic glass was also studied using HREM and high angle annular dark-field (HAADF) techniques. Crystalline clusters with sizes of about 1-2 nm were detected in the as-cast Zr71Cu13Ni10Ti 3Al3. In the HAADF image, bright contrasts extending as small as 2 nm were found to fluctuate locally, indicating a local compositional fluctuation caused by nanoscale phase separation. © 2004 Elsevier Ltd. All rights reserved.

Research Area(s)

  • B. Glasses, metallic, D. Microstructure, E. Simulations, F. Diffraction (electron, neutron and X-ray), F. Electron microscopy, transmission, Monte Carlo

Bibliographic Note

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Citation Format(s)

Nanoscale phase separation in metallic glasses studied by advanced electron microscopy techniques. / Hirotsu, Y.; Hanada, T.; Ohkubo, T.; Makino, A.; Yoshizawa, Y.; Nieh, T. G.

In: Intermetallics, Vol. 12, No. 10-11 SPEC. ISS., 10.2004, p. 1081-1088.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review