Durch Zwischengitteratome bedingte Relaxationserscheinungen in kaltverformtem Kupfer

The internal friction of polycrystalline 99,999% purity-copper wires deformed at 23°K to 4% elongation was measured with an inverted torsion pendulum. Besides the wellknown maxima at 50°K (Bordonimaximum) and 165°K a maximum at 250°K was found. From the study of the annealing behaviour and structure of this maximum it is concluded, that the reorientation of dumbbell interstitials in the stress field of the applied force is the process responsible for this internal friction maximum.