The cyclic stress—strain response and dislocation structures of Cu-16 at.%Al alloy II: Polycrystalline behavior

Abstract In order to check whether or not the relationships which exist for the cyclic stress-strain behavior and dislocation structures of monocrystalline and polycrystalline copper also apply to a material of planar slip character, we have strain cycled Cu-16at.%Al alloy by a step test, by test at constant amplitudes and by tests at ultrasonic frequencies. Al-though monocrystalline Cu-16at.%Al alloy shows a plateau in its cyclic stress-strain curve, polycrystalline alloy does not for the small grain size that we used. Nevertheless the dislocation structures which occur in polycrystals are similar, for both the matrix and the persistent slip bands, to those which occur in single crystals. Thus we predict the occurrence of a plateau in a large-grain-sized alloy and claim wide agreement with the relationship found for copper.

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