Grain- and phase-boundary stress effects in nanocrystalline materials

Based on the principal of virtual work, we derive an equation that describes the balance between volume and interface stresses in a particulate two-phase nanocomposite belonging to the class of random heterogeneous materials. Extracting absolute values of interface stress requires precise measurement of residual-strain-free lattice parameters and determination of interface area as well as volume fractions of phases. We find a value of 3.5±0.2Nm-1 for the isotropic phase-boundary stress of the Ag/Ni interface and a value of 0.67±0.1Nm-1 for the grain-boundary stress of Ag. If we compare this value with literature values for Gd, Pd and Fe, it appears that grain-boundary stress linearly correlates with the melting temperature of those elements.