The change of the (α + γ) microduplex structure during annealing in an Fe-26%Cr-7%Ni alloy has been investigated with emphasis on the change in the misorientation of the α matrix subgrain boundaries with subgrain growth in a large range of subgrain size. A long time holding up to 360 ks at 1273 K caused significant structure coarsening, and the growth of the α matrix subgrains and γ particles obeyed the third power law. On the other hand, the average misorientation of the α subgrain boundaries changed insignificantly, even though the α subgrain size markedly increased from 2.6 to 15.6 μm. This insignificance in the misorientation resulted from the fact that the variation of the local lattice rotation in the α matrix is not monotonic but periodic, and no long range lattice curvature exists.
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