The four kinds of specimens (KCl:Mg2+, Ca2+, Sr2+, or Ba2+) were deformed by compression along the <100> axis at 77－254K and ultrasonic oscillatory stress was applied in the same direction as the compression. The activation energy for overcoming of the impurity by a dislocation was determined by examining the relative curve of strain-rate sensitivity and stress decrement due to the oscillation. The activation energy increases with the divalent ionic size. Fleischer’s model attributes this to the difference of tetragonality around the divalent ion-vacancy dipole for each specimen.
moving dislocation
plastic deformation
strain-rate cycling tests
ultrasonic oscillation
force-distance profile between a dislocation and an impurity
activation energy