Letter | Published:

Unloading Effects in Copper Single Crystals

Nature volume 180, pages 14761477 (28 December 1957) | Download Citation



Haasen and Kelly1 have observed a small yield point on retesting previously strained single crystals of aluminium and nickel at the same or lower temperatures than the initial deformation. The effect occurred only when the crystals were unloaded between tests, and no yield point was found at low stresses. Annealing at 300° K., between tests at 90° K., increased the magnitude of the yield phenomenon and much larger yield points were observed when the second deformation was carried out at a lower temperature than the first. Haasen and Kelly attributed the effect to the rearrangement of dislocations during unloading.

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  1. 1.

    , and , Acta Met., 5, 192 (1957).

  2. 2.

    , Phil. Mag., 46, 1169 (1955).

  3. 3.

    , Phil. Mag., 1, 489 (1956).

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  1. Metallurgy Division, Atomic Energy Research Establishment, Harwell, Berks. Sept. 26.

    • M. J. MAKIN


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