Structure and Dynamics of Shear Bands in Metallic Glasses and Nanophase Composites

Abstract

We have performed quantitative high-resolution transmission electron microscopy studies of the structure of shear bands in metallic glasses. We observe the formation of numerous nanometer-scale voids in shear bands produced under predominantly tensile loading. These void-like defects appear to result from the coalescence of excess free volume in the active shear band when the plastic flow ceases. By comparing the free energy of the shear band with that of the undeformed glass, we show that the void formation process is thermodynamically possible. The presence of the voids can explain several features of the mechanical behavior of metallic glasses, including the difference in plastic strain observed between tests conducted in uniaxial tension and those done in uniaxial compression.

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Document Details

Document Type
Technical Report
Publication Date
Feb 06, 2003
Accession Number
ADA413556

Entities

People

  • Todd C Hufnagel

Organizations

  • Johns Hopkins University

Tags

Communities of Interest

  • Energy and Power Technologies
  • Weapons Technologies

DTIC Thesaurus Topics

  • Amorphous Materials
  • Band Structures
  • Composite Materials
  • Electron Microscopes
  • Electron Microscopy
  • Energy
  • Free Energy
  • Glass
  • Glass Transition Temperature
  • Materials
  • Materials Science
  • Metallic Glass
  • Microscopy
  • Physical Properties
  • Shear Bands
  • Transition Temperature
  • Two Dimensional

Fields of Study

  • Physics

Readers

  • Fluid Dynamics.
  • Materials Science (Mechanical Engineering).
  • Materials Science and Engineering.

Technology Areas

  • Microelectronics