ACCOMMODATION OF THE LATTICE MISMATCH IN A AG/NI HETEROPHASE BOUNDARY

Using the embedded-atom method, we model atomistically the compensation of the misfit-induced stresses in a "cube-on-cube" oriented Ag/Ni bicrystal with a (011) interface plane, in which zones of maximum misfit (misfit dislocations) run along the [100] and the [011BAR] directions. The ideal interface corresponds to an abrupt transition between Ag and Ni. The interfacial enthalpy is found to be lowered by the introduction of vacancies on the Ni side (equivalently, vacancies are trapped on the Ni side of the boundary). Pursuing this perspective, we find that the interfacial enthalpy is lowered considerably by the removal of a complete line of Ni atoms along the [011BAR] direction from the Ni side of the boundary. The minimum enthalpy configuration consists of a Ni layer whose atomic density is reduced by 16%, sandwiched between the ordinary Ni and Ag lattices. A detailed analysis of the vacancy-formation process shows that atomic relaxations make the main contribution to the low vacancy-formation enthalpies at the boundary.