The internal friction of cold-worked single crystals and polycrystalline specimens of high-purity copper has been measured in the temperature range from 20 to 200 K at frequencies between 10 and 25 kHz. The Bordoni peak was found to occur at approximately the same temperature for crystals of <111> and <100> orientations as for polycrystalline specimens. It was displaced to a slightly higher temperature for crystals of <110> orientation, but this shift is attributed to the fact that smaller stresses were used in the prior deformation of these specimens; the peak in these crystals is relatively broad and asymmetric. Thus these results at kilohertz frequencies do not show the orientation dependence of the Bordoni peak which has been observed by other authors at megahertz frequencies.

The internal friction of cold-worked single crystals of high-purity silver has been measured in the temperature range 20-160 K at frequencies between 13 and 18 kHz. The temperature of the Bordoni peak was found to be substantially independent of the orientation of the crystal. This result is consistent with earlier work on gold and copper single crystals at kilohertz frequencies; none of these metals shows the orientation dependence of the Bordoni peak which has been observed at megahertz frequencies.

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