Recovery of Lattice Parameter and Electrical Resistivity in Low-Temperature Neutron-Irradiated Copper

Abstract

The fast---neutron-irradiation-induced change and subsequent isochronal annealing recovery of the lattice parameter and electrical resistivity of copper were studied. A wire resistivity specimen and single crystal were irradiated together in liquid helium and transferred to a cryostat without warm up. The simultaneous recovery of both properties was measured at 4.2\ifmmode^\circ\else\textdegree\fi{}K following isochronal anneals to temperatures as high as 675\ifmmode^\circ\else\textdegree\fi{}K. The results of the three successful experimental runs were in good agreement. An analysis, based on linear superposition of the effects of the individual defects, is presented as the simplest and most direct approach to determine the migration mechanism as a function of temperature. The most significant and unambiguous conclusion of this analysis is that stage-III recovery in copper (220-280 \ifmmode^\circ\else\textdegree\fi{}K) is due to vacancy migration. Alternative explanations in terms of more complex phenomena appear less probable, but cannot be excluded with certainty.