Temperature dependence of the activation volume and the flow stress of Cadmium single crystals
Coplin, Donald Herbert
Roberts, John M.
Master of Science
Cadmium single crystals of 99.994% purity were tested by the strain rate change method to determine the activation volume over the temperature range from 77°K to 508°K. The temperature dependence of the flow stress and of the work hardening coefficient over the same range was also investigated. All three parameters exhibited an anomalous behavior at a temperature of about 275°K from that predicted by a single mechanism model as discussed by Seeger for the same temperature range. Theories are discussed to explain the observed results for cadmium as veil as to be consistent with previously reported results on magnesium and zinc. It is concluded that the Seeger approach explaining these deformation parameters is correct with some extension and modification. It is believed that the deformation, behavior is of a different nature below the temperature of about 275°K from that above. Specific models for these differences are discussed.