Stress Induced Migration of ⟨112⟩ Symmetric Tilt Boundaries

Abstract

Stress induced grain boundary migration of ⟨112⟩ symmetric tilt boundaries with misorientation angles ranging from 3.5° to 40° was investigated by the use of aluminum bicrystals.
When the misorientation angle exceeded about 5°, grain boundaries did not migrate under the stress at room temperature. However at elevated temperatures, the grain boundaries with misorientation angles smaller than 30° migrated under the stress. The migration velocity (v) varied with tensile stress (σ) and temperature (T) according to the following equation:
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\ oindentwhere A(θ) is a numerical factor depending on the misorientation angle (θ), n=1.0±0.2 and Q=76±8 kJ/mol.
Grain boundary sliding occurred and the stress induced migration was not observed for the misorientation angles larger than 30°. On the other hand, the mobility of the grain boundary migration driven by the grain boundary energy was low for the boundaries with misorientation angles smaller than 30° but was high for the boundaries with misorientation angles larger than 30°.
These results suggest that the grain boundaries with misorientation angles smaller than 30° contain dislocations and defect areas, whose migration rate is controlled by the grain boundary self-diffusion.