Study of intrinsic point defects in Tantalum after plastic deformation at liquid helium temperatures

Abstract

An apparatus permitting extensive plastic deformation o f wires o f high melting point b.c.c. metals at liquid helium temperatures is described. The recovery o f the electrical resistivity of pure and oxygen-doped tantalum deformed at liquid helium temperatures was measured up to 540 K. In this temperature interval, only one major recovery stage superimposed on a continuous background recovery and located between 240 and 300 K was found. It is controlled by the long-range migration of an intrinsic point defect with a migration enthalpy o f 0.70 ± 0.03 eV. The results are discussed in the context of high temperature and irradiation data, and it is concluded that the defect migrating in this “stage III" is a self-interstitial configuration.