The energy of formation of a double kink was calculated as a function of stress for various boundary conditions, values of elastic constants, and different dislocation lengths. The activation energy of the double kink mechanism is considered to be the formation energy of the double kink. Once a double kink has formed, the lateral motion is an athermal process. The interaction energy between the kinks and between the kinks and the remaining portions of the dislocations was found to be small compared to the formation energy of the double kink. There is fair agreement between the calculated activation energies and the experimental values. The potential energy versus displacement curve for the formation of successive double kinks was calculated for a finite dislocation. The potential energy is found to decrease to a minimum and then increase monotonically as the displacement increases. This potential energy profile is examined in terms of low temperature internal friction and as a possible explanation of the decrease in activation volume with strain for iron deformed at low temperatures.
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