| Abstract Scope |
Abnormal grain growth, in which a small fraction of grains grow at a faster rate than their neighbors, results in heterogeneous microstructures with unpredictable performance. Special grain boundaries with high mobility have been previously proposed as responsible for the growth advantage. As the microstructures evolve, these grain boundaries change structure, leading to questions about how such growth is sustained. Here, laboratory-based diffraction contrast tomography (LabDCT), which maps the full 3D microstructure non-destructively, is used to correlate grain boundary character and velocity during abnormal grain growth in commercially pure nickel and calcia-doped alumina. In nickel, abnormal grains grow discontinuously with distinct morphology changes associated with special Σ3 grain boundaries. In calcia-doped alumina, the abnormal grains maintain their crystal shape and show an almost uniform change in dimension. The implications of these behaviors on how and why abnormal grain growth occurs will be discussed. |