Non-equilibrium Interface and Surface Dynamics

The Relationship Between Grain Boundary Energies and Grain Boundary Complexion Transitions

Gregory S. Rohrer

Carnegie Mellon University

It has recently been discovered that the structure and composition of grain boundaries can abruptly change, leading to discontinuous changes in grain boundary properties, such as mobility. These different structural and chemical states are referred to as complexions. We have recently conducted experiments to examine the link between grain boundary energy and complexion transitions and the influence that they have on the grain boundary populations. In doped aluminas, the relationship between grain boundary energy and grain boundary population varies with the complexions in the sample. We have also examined the competition between complexion transitions and precipitation reactions. The findings indicate that there is an inverse correlation between the energy of the precipitate-host interphase boundary and the temperature range in which that system undergoes complexion transitions. It is proposed that precipitation and complexion transitions compete as two different paths for partitioning excess solute in the grain boundary.