A new mathematical model for the internal friction due to interaction between geometric dislocation kinks and foreign interstitial atoms has been developed which contains the feature of diffusing interstitials with the influence of the attraction field of kinks.

**Coordinate Transformation: Global (x) to Local Coordinates (u) **

Assumption: Nearest-Neighbor Interaction between the Kinks

The time and space variables are normalized as;

with respect to the driving frequency and;

with respect to the distance travelled by a spread-out interstitial during one period of the motion.

**Calculation of Dynamical Internal Friction Coefficient**

where

**Wdisp:** Energy Dissipated per cycle by the total kink population

**WE:** Maximum elastic energy stored in the kink chain during one cycle of external excitation