Current research on nanocrystalline metals and nanoscale multilayer thin films suggested extraordinary plastic strength was due to confinement of slip to individual grains or layers. To assess the magnitude of confinement, a Peierls model of slip transmission of a screw dislocation across a coherent, non-slipping interface was presented. The results reflect that large interfacial barriers to transmission were generated by rapid fluctuations in dislocation line energy near the interface due to elastic modulus mismatch, stacking fault energy mismatch, and antiphase boundary energy for transmission into an ordered phase. Coherency stress was predicted to dramatically alter the dislocation core configuration and impart additional strength regardless of the sign. Contributions to strength were not additive due to non-linear coupling via the dislocation core configuration. The predicted barrier strength for a coherent (001) Cu/Ni interface was comparable to atomistic (EAM) results but larger than estimates from hardness data.

Transmission of a Screw Dislocation across a Coherent, Non-Slipping Interface. Y.Shen, P.M.Anderson: Journal of the Mechanics and Physics of Solids, 2007, 55[5], 956-79