Interface stress in polycrystalline materials: The case of nanocrystalline Pd

Based on a generalization of a capillary equation for solids, we develop a method for measuring the absolute value of grain-boundary stress in polycrystalline samples having a large interface-to-volume ratio. The grain-boundary stress in nanocrystalline Pd is calculated from x-ray diffraction measurements of the average grain size and the residual-strain-free lattice spacings, yielding a value of 1.2+/-0.1 N/m . The random distribution of crystallite orientations in the sample suggests that this value is characteristic of high-angle grain boundaries in Pd.