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A peak in the internal friction due to dislocations in aluminum was found well below the temperature of the usual Bordoni peak. Measurements were made from 25 kc to above 1 Mc, yielding a relaxation peak that varied with frequency over a temperature range of 21^∘{}K to 31^∘{}K. The activation energy of this peak was found to be 0.024 ev.
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Lax et al. (1959) studied this question.
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