Dominique Chatain1, Paul Wynblatt2, Anthony D. Rollett2, Gregory S. Rohrer2

1Aix-Marseille University, CNRS, CINaM, UMR 7325, 13288 Marseille, France.

2Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.


How and why do two fcc metals, of very different lattice parameters, choose their relative orientations across their hetero-interface?

To answer this question, the orientation relationships (ORs) of submicron Ag crystals equilibrated on more than 200 Ni(hkl) surfaces, spanning the whole stereographic triangle, have been determined by EBSD. The observed ORs do not conform entirely to either of the common beliefs: (i) that Ag will form with its (111) plane parallel to any Ni(hkl) surface, or (ii) that the OR between Ag and Ni will be cube-on-cube. Although the cube-on-cube OR is indeed observed, three other types of OR have been identified.

The experimental results are consistent with MD simulations, which show that the ORs are related to the step alignment which develops in the early stages of interface formation and which leads to minimum energy interfaces. This is a new concept for the interpretation of hetero-epitaxy and/or ORs.