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EDX and EELS Studies of Segregation in STEM

  • J. M. Titchmarsh
  • I. A. Vatter
Part of the NATO ASI Series book series (NSSB, volume 203)

Abstract

Segregation in materials can be broadly divided into two types; equilibrium (ES) and non-equilibrium (NES). In the former1 the segregating species is assumed to have reached a steady-state equilibrium at a particular temperature such that the rate of capture at a sink exactly balances the rate of evaporation from the sink by thermal excitation. Subsequent rapid cooling to room temperature does not significantly alter the segregation profile. A simple concentration step change can be assumed to occur at the matrix-sink interface, with no significant concentration gradients present in the adjacent matrix. With NES, the concentration profile at the boundary is determined by the capture of solute atoms during quenching from an elevated temperature2 and so solute concentration gradients occur in the matrix adjacent to the boundary. The extent of the profiles is determined by the diffusion rates of the migrating species, and these can also be on the scale of inter-planar spacings. Much wider depletion and segregation profiles can also be produced by precipitation reactions at grain boundaries during high temperature anneals. Although point defects and linear defects can trap solute atoms, in this paper we shall consider sinks to be two-dimensional, i.e. grain boundaries, precipitate/matrix interfaces.

Keywords

Ferritic Steel Foil Thickness Probe Size Boundary Segregation Chromatic Aberration 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Plenum Press, New York 1989

Authors and Affiliations

  • J. M. Titchmarsh
    • 1
  • I. A. Vatter
    • 1
  1. 1.Fracture Studies GroupHarwell LaboratoryDidcot, OxonUK

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