Resistive Stress for the Thickening of Twins in Tin Crystals

The steps caused by the screw dislocations on the twin boundary of β-tin crystal are responsible for the thickening of mechanical twins, since all of these steps are composed of twin dislocations in the case of β-tin crystal. Possible origins of the stress needed to the motion of twin dislocations are first, the stress for the twin dislocations to pass through the forest of screw dislocations, and second, the stress to form the stacking fault in the twin. Numerical estimations are in consistency with observations.