Initiation of geometric roughening in polycrystalline metal films

The mechanics of plasticity-induced roughening of initially planar polycrystalline metal films upon thermal cycling is presented. The emphasis is on films of FCC metals having grain size comparable to their thickness. In the model, the elastic substrate imposes a biaxial in-plane mismatch strain on the film. Calculations demonstrate how surface undulations develop with a length scale governed by the grain size, when plastic slip initiates above a critical strain. Under monotonic straining, the undulation amplitude grows in proportion to the imposed strain with extent dependent on the slip anisotropy. Upon cyclic plastic straining, three growth stages have been identified with the possibility of substantial roughness development. To cite this article: G. Parry et al., C. R. Mecanique 336 (2008).