Recovery of electron-irradiated zirconium at low temperatures

Abstract

The low-temperature recovery of the electrical resistivity of polycrystalline zirconium was measured after electron irradiation below 8 °K. The material used in this irradiation was the same low oxygen material (0.015 at.%) used by Swanson to study recovery after deformation at 4.2 °K. Substage IB was found to be only of the order of 4% of the irradiation-induced resistivity change, compared to ~6% observed by Swanson after deformation. Stage I (4.2 to 160 °K) in Zr contains six substages, while stage II (160 to 310 °K) contains only one substage after electron irradiation. While no study of kinetics was made, it seems likely that close pair-annihilation processes are responsible for the recovery spectrum below 118 °K and that longer-range defect migration occurs in the neighborhood of 140 °K.