Shape of Moving Grain Boundary and its Influence on Grain Boundary Motion in Zinc

摘要

The migration of individual special [1010] tilt grain boundary (GB) with Σ = 15 and misorientation angle 29° in Zn bicrystal have been investigated. The stationary shape of migrating GB has been studied and the migration rate has been measured by optical microscopy in situ between 558 and 683 K using polarized light. In certain experimental runs the migrating GB is faceted and moves thermally activated. Its kinetics follows the Arrhenius type dependence despite the fact that shape of moving GB depends on temperature. After detachment from impurity cloud the [1010] tilt GB migrates activationless in the temperature interval 618/683 K. The detachment temperature is 618 K. The non-physically high value of the apparent migration activation enthalpy can appear due to the change of GB shape from faceted to smooth and back.