Motion of [1 0 0]-tilt grain boundaries under cyclic stresses

The motion of planar symmetric [1 0 0]-tilt grain boundaries in high purity aluminium under cyclic elastic deformation conditions was investigated. Bicrystals were fabricated to obtain grain boundaries with different misorientation angles between 3.7° and 42.5°. They were deformed under cyclic tension and compression at elevated temperatures and maximum stresses of ±0.5 MPa. Grain boundary displacements were measured by optical microscopy. After deformation activation parameters were calculated from an Arrhenius analysis of the displacements as a function of the temperature. Two regions can be distinguished; within each region the activation enthalpy was found to be constant. The misorientation angle which separates the two regions can be correlated with the transition angle between low and high angle grain boundaries. The mechanism of cyclic motion of [1 0 0]-boundaries is discussed in terms of migration and sliding. The results were compared with stress-induced grain boundary motion under the influence of a constant shear stress.