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Coarsening of γ′‐precipitates in nickel‐base superalloys and of δ′‐precipitates in aluminium‐rich aluminium–lithium alloys is investigated by analytical transmission electron microscopy. The growth rate of the particles increases with their volume fraction. This increase is described best by Ardell's [6] model. The γ′‐volume fractions of the superalloys are independent of the annealing time t. In the case of the Al–Li alloys the analogous statement holds only if t is long enough to yield average δ′‐particle radii of 9.4 nm or more. For shorter heat‐treatments the δ′‐volume fraction increases strongly with t.

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