Low-Frequency Measurements on the Bordoni Internal Friction Peak in Copper

An apparatus is described for the measurement of the internal friction of metals over the temperature range of 4°–300°K at a frequency of the order of 10 cps. The Bordoni internal friction peak was observed in pure polycrystalline copper at 62°K at a frequency of 13.4 cps. By comparison with measurements at higher frequencies, a value of 0.14 ev is deduced for the activation energy. The width of the Bordoni peak is discussed in terms of distributions of activation energies and attempt frequencies.