COHERENCY STRAIN EFFECTS IN METALLIC BILAYERS

Since its discovery, the so-called 'supermodulus effect' has attracted considerable attention, both in view of possible applications and because of its intrinsic fundamental scientific interest. Recent experimental investigations have, however, cast doubts on the very existence of the effect, or at least on its magnitude. From a theoretical point of view, several models have been proposed to explain the effect, but none is fully convincing. In the present paper we investigate the coherency strain model, which we believe may yield the most plausible quantitative explanation of the supermodulus effect. We follow the approach first proposed by Jankowski and Tsakalakos, but, in addition to other modifications, we evaluate the biaxial modulus for a deformation in the [111] direction, as observed experimentally, rather than the [100] direction, as chosen by Jankowski and Tsakalakos (probably because it was easier to determine the biaxial modulus in this rather than in the [111] direction).