  In this work, we experimentally establish the isothermal nanofacet evolution
at an asymmetric tilt grain boundary in the Cu-Ag system using a diffusion
couple approach. We investigate the nanofacet formation along the grain
boundary in dependence of the Ag solute excess concentration. The initial grain
boundary dissociates into asymmetric Ag-lean segments and Ag-rich symmetric
(210) segments. Increasing Ag excess leads to an increase in Ag-rich facet
segment length, while the length of the asymmetric facets remains constant.
From this, we construct a grain boundary nanofaceting diagram deduced from our
experiments relating local atomic structure, overall inclination and Ag solute
excess.
