Use the book attached in the following link and any other relevant
source to answer the following questions. https://drive.google.com/file/
d/1-kN9QMjGsyeQXoBXHLt8kP9IwC1oswz-/view?usp=sharing
5. Examine figure 2.57 in Brandon & Kaplan which shows a TEM diffraction
pattern from a single grain of -Fe (BCC Fe). Examine the apparent symmetry Fe (BCC Fe). Examine the apparent symmetryα-Fe (BCC Fe). Examine the apparent symmetry
of the pattern (note spot diam is used to indicate the intensity of the diffracted
beams) – what is the zone axis for this pattern? (hint:the diffraction pattern
MUST reflect AT LEAST the symmetry of the real crystal along that direction
but could appear to be higher symmetry. Index the pattern, remembering the
following rules:
a. The zone axis (vector that the e-Fe (BCC Fe). Examine the apparent symmetry beam is travelling along) points straight out
of the page and is centered in the center of the pattern
b. The in-Fe (BCC Fe). Examine the apparent symmetry plane vectors to the diffraction spots are the momentum transfer
vectors and reciprocal lattice vectors ∆k=G. Since the zone axis is normal to
the page and all the G vectors are in plane, the dot products of G*zone axis
vector must be zero.
c. The radius from pattern center to each spot is the magnitude of the G
vector times a scale factor. So you can take ratios of these radii and invert
them to get the ratios of d-Fe (BCC Fe). Examine the apparent symmetry spacings in real space. The d-Fe (BCC Fe). Examine the apparent symmetry spacing as function of
hkl for a cubic crystal is equation 2.38 in B&K book.
discussion in context of a TEM diffraction pattern. Also read sections 5.6.4-Fe (BCC Fe). Examine the apparent symmetry
5.6.6. What changes in the discussion for the OIM / EBSD context as opposed
to TEM context?
