Mechanical Spectroscopy in Nitrogen Implanted Copper

The effects of nitrogen irradiation employing a plasma focus device on high purity polycrystalline copper are shown. It should be pointed out, that the effects of implantation process depend strongly of the previous thermal state of the sample. In fact, a new damping peak at approximately 750 K appears in irradiated samples which were previously annealed during 1 hour at 1073 K, but neither new peak at 750 K was measured in samples previously annealed during 5 and 15 hours. However other new peak appears at 1000 K. Moreover in the first case non hysteresis effects between a run up and down in temperature were found in both damping and modulus, but in the second one strong hysteresis effects appeared