On the generality of a preferred orientation at interfaces of crystals

The generality of a preferred orientation at crystalline interfaces is considered by analyzing previously reported computed grain boundary energies of metals from an epitaxial thin film perspective. 388 fcc and 408 bcc boundaries are sorted in a fashion that is conceptually analogous to combinatorial substrate epitaxy (CSE) experiments previously reported for non-isostructural oxide film–substrate pairs. CSE observations are briefly reviewed, indicating that there is a single preferred OR for all film–substrate pairs of close-packed oxides, regardless of the interface plane, which is called the eutactic OR. The eutactic OR is shown to be structurally similar to the Σ3 coincident site lattice (CSL) OR for grain boundaries of metals. Based on low-energy outliers in the grain boundary populations, it is shown that the Σ3 CSL OR (the common twin misorientation) is the preferred OR for both metal families, also regardless of the interface orientation. The combined observations for metal grain boundaries and epitaxial oxide films are consistent with the existence of a single preferred OR (a Σ3 OR) at interfaces of crystals.