210 Prakt. Met. Sonderband 52 (2018)
higher annealed and unloaded specimen (TAO03) intra-block misorientations can be >10°.
Also the ability to qualitatively visualize how dislocations arrange to dislocation cell walls is
demonstrated on the same OIM data. The formation of cell walls is highly effective to
reduce the strain energy compared to the random distribution of dislocations, resulting in a
thermodynamically more stable state.
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Fig. 2: Specimen TAOQ3. Left: Euler-angle coloring of area around a block and intra-block
misorientation relative to the point marked by an arrow. Right: Geometrically necessary
dislocation (GND) density (given in multiples of 10"? m2) with maximum considered
misorientation of 15° (larger misorientations are ignored resulting in white areas) and first
nearest neighbors (pixels) gradient calculation.
Next, the interface or boundary character distribution is investigated. (Fig. 3) shows the
effect of loading on the relative amount of low-angle, coincidence site lattice (CSL) and
high-angle (>15°) interfaces. While in the higher annealed sample (TA03) the fraction of
CSL and high-angle boundaries is almost the same, fewer CSL boundaries are formed in
tension (TR25) and even fewer with a shear load (TR32). It should be noted that CSL
interfaces are mainly high-angle interfaces. However, the fraction of high-angle interfaces
is almost the same in the three samples. The stresses due to external loading exacerbate
the formation of (low energy) CSL boundaries such that more low-angle boundaries are
formed. The latter are also partly responsible for the contrast of TR32 in (Fig. 1).
Finally, the overall texture of the samples is compared. In the case here static
recrystallization, recovery and the (loaded) transformation on cooling influence the final
texture. (Fig. 4) shows the 100, 110 and 111 pole figures of the three samples.
Interestingly, tensile loading (TR25) leads to a comparably sharp texture considering that
the maximum value is almost twice as large compared to the other two specimens. evs
Moreover, it exhibits the most symmetric texture, even more symmetric than the unloaded. a
higher annealed specimen (TA03).
SU
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