A polycrystal undergoes microstructural changes to reach a lower energy state. In particular, the system evolves so as to reduce the total grain boundary energy. A simple 2-dimensional model of a polycrystal comprised of randomly oriented crystalline grains suggested that energy minimization reduced or eliminated any spatial correlation among high-energy grain boundaries. Thus grain boundary engineering not only reduced the density of high-energy boundaries, but also prevents their organization into a coarse, albeit discontinuous, network.

Spatial Correlation of High-Energy Grain Boundaries in Two-Dimensional Simulated Polycrystals. C.DeW.Van Siclen: Acta Materialia, 2007, 55[3], 983-9