Grain boundary migration in Fe-3%Si bicrystal

Migrations of 〈110〉 tilt boundaries in Fe - 3% Si alloy bicrystals have been investigated by Sun and Bauer technique as a function of misorientation angle, driving force and temperature. Two regions of different migration behaviour are observed: a change in the mobility occurs as the driving force decreases. In the higher driving force region, the activation energy for grain boundary migration is ca. 2/3 of the energy for Fe - atom bulk self - diffusion, indicating that the boundary motion may be governed by the grain boundary diffusion. While in the lower diving force region, the activation energy for migration increases to ca. 220kJ/mol which agrees well with the energy for intrinsic - diffusion of Si in α-Fe, suggesting that grain boundary should move dragging Si atmosphere. Further, the rate of grain boundary migration is found to depend on misonentation, i. e., the mobility for coincidence boundaries, especially Σ9 boundary, are higher than that for a random boundary. The results obtained here will be discussed from the viewpoint of the interaction between grain boundary and solute atom.