Specimen Preparation and Electron Backscatter Diffraction
Danka Katrakova, Frank Mücklich, Saarland University, Saarbrücken, Germany
Morten J. Damgaard, Struers A/S, Denmark
Abstract
Electron BackScatter Diffraction (EBSD) is meanwhile well established in materials science. The
method allows imaging of the true microstructure of crystalline materials, since it is based on local
. lattice diffraction in a very thin surface layer. The contrast is given through the orientation
differences of neighbouring grains. Residual surface deformation leads to blurring and poor contrast
of the respective electron backscatter patterns (EBSP). On the one hand, this suggests the use of the
pattern quality as a measure for the preparation quality. On the other, it requires modification and
adjustment of the standard preparation methods for the EBSD application.
In this study a set of materials that differ in their preparation behaviour and in their EBSD
information depth are prepared in a manner that EBSPs of good quality are achieved. Some
wed Kor guidelines are summarized.
Kings Introduction
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1/30 md The aim of the specimen preparation is to obtain an even and deformation free surface so that the
d 2eitzt true microstructure of the material can be visualized. In general, the depth of scratches is much
’ lower and easier to reduce than the depth of deformation. It is directly proportional to the abrasive
particle size (Fig.1). Mostly a scratch free even surface is achieved. That is not difficult to control
by light microscopy or even by special methods imaging topography with high resolution like white
light interferometry. But this surface is not necessarily deformation, or more generally, distortion
free (Fig. 2). In fact, it is very difficult to make this distortion visible or to measure it.
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2 Particle Size of Grinding Compound in um
Fig. 1: Depth of surface roughness and deformation Fig. 2: Schematic showing the cross section
' as a function of the abrasive particle size [99Pet] of a surface region from a mechanically
> ground and polished sample [99Pet]
The EBSD can be seen as a contrasting technique that reveals really true microstructure because it
is not applicable if distortion in the crystal lattice induced by preparation is still present and also
welt Mein Dank because contrast is based on orientation differences. The information depth of the method is very
tale. Ebenso sit low compared to estimated residual distortion zone. For example if a 70:30 brass is finally polished
ni das neue DMR with v-Alumina (0-0.1 um) the depth of roughness is about 0.03 um, whereas the depth of
dar Untersuchun-
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