Compensation effect in grain boundary internal friction

Experimental evidence is provided for the occurrence of the compensation effect, i.e., a linear relationship between the activation enthalpy and the logarithm of the pre-exponential factor, for grain boundary internal friction. The results of internal friction measurements in bicrystals of high purity Al with structurally different grain boundaries were analyzed. The extracted compensation temperature was found to be the same as for grain boundary migration and diffusion of solutes along grain boundaries in Al bicrystals. This temperature divides the investigated temperature range of the internal friction peak into two regimes, with different relations between the magnitude of relaxation time and enthalpy of activation.