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grains have an <111 > direction normal to the sample sur-

face. There are also some areas that are green in the map and

these areas have an <110 > direction parallel to the surface

normal. The inverse pole figure map with respect to the X

direction looks totally different to the Z inverse pole figure

map. Both of these are shown in. Fig. 29.20.

29.2.7 Other Map Components

Once the orientations of the pixels in an array are known, it is

now possible to add additional information to the maps.

There are many possible components the can be plotted based

on EBSD data. One of the easiest components to add is that of

grain boundaries. Grain boundaries are the planes (which

intersect the planar surface as lines) that separate two regions

of different crystallographic orientations. It is fairly trivial to

calculate the change in orientations between two pixels. If we

do this for an entire map we can then plot lines where the dif-

ference in orientations between two adjacent pixels exceeds a

predefined limit. It is typically assumed that a grain boundary

is represented by a change in orientation that exceeds 10°.

. Figure 29.20 has black lines plotted where the change in ori-
entation exceeds this limit and thus the map shows the size of
individual grains even though they are of consistent color due
to the grain orientations with respect to the sample normal.

29.2.8 Dangers and Practice of “Cleaning”

EBSD Data

Many of the currently available software platforms for EBSD

allow users to modify the inverse pole figure maps in order to

improve their appearance only (Brewer and Michael 2010 ).

There are always pixels in a map that are either not indexed due

to pattern quality or many other reasons or that are mis-

indexed due to some sort of symmetry issues or multiple pos-

sible solutions to the bands that are found. These cleaning

routines normally perform two separate operations. The first

step is to remove the mis-indexed pixels. These pixels usually

IPF colouring

Y0

Iron fcc

111

001 101

. Fig. 29.19 Typical color key used for inverse pole figure maps. This
color key is used to color each pixel in an image to produce an inverse
pole figure map or image. Thus, if a pixel has a <001 > direction parallel
to a specific direction then we use this inverse pole figure key to plot
that pixel as red. Or conversely, if we observe a red pixel in an orienta-
tion map we know the orientation of that pixel is close to <100 > paral-
lel to the plotted direction
. Fig. 29.20 Inverse pole figure maps from the X-direction (left) and the Z-direction (right). This is the same data that is shown in. Figs. 29.9
and 29.10. Inverse pole figure maps show the pixel-by-pixel or spatial arrangements of the crystal orientations (Bar = 5 μm)

Chapter 29 · Characterizing Crystalline Materials in the SEM