Microstructural characteristics governing the lattice rotation in Al-Mg alloy using in-situ EBSD

Abstract The lattice rotation behavior of Al-4%Mg alloy subjected to tensile deformation is studied through in-situ electron backscatter diffraction (EBSD). The emphasis is laid on the effect of the orientation of neighbors, second phase particles, and the local deformation state on the lattice rotation characteristics. The results obtained show that the lattice rotation response of grains with similar initial orientation is largely different characterized by differences in the magnitude of rotation, rotation rate, rotation path, and activation of slip systems. The rotation path of grains towards reaching the stable end orientations is found to be governed by the microstructural relationships such as the misorientation and fraction of grain boundary segment shared with the immediate neighbors. Also, the local reorientations associated with the second phase particles, slip plane kinking, and triple junctions due to disruption of the slip activity and deformation heterogeneity of the neighbors significantly affect the average rotation of the grains and the rate of rotation. The rotation path of such local lattice rotations in grains is not strictly bound by the microstructural relationship with the neighbors. Further, when the shape change of grains introduced by local deformation mechanisms is significant, lattice rotations accompanying slip deviate from the rotation tendency based on the microstructural relationship with the neighbors. The observed dependence of lattice rotation of grains with simple slip activity on the misorientation and fraction of grain boundary segment shared with the immediate neighbors is also validated through full-field crystal plasticity simulation using DAMASK software. Simulation results also reveal the state of stress in grains that favor the initiation of local deformation mechanisms and the associated lattice reorientations observed experimentally. Altogether, this study renders gainful insights on the dependence of the lattice rotation of polycrystalline Al-4%Mg alloy on the microstructural characteristics which are of significant considerations to the development of constitutive description of crystal plasticity models in improving the accuracy of predicting the bulk engineering properties and texture development.