We study the effects of grain boundary adhesion and grain size on the ductility of thin metal films well bonded to polymer substrates, using finite element method. It is shown that the ductility of polymer-supported metal films increases approximately linearly as the grain boundary adhesion increases, and as the grain size decreases. A rule-of-thumb estimate of the ductility of polymer-supported metal films agrees well with the simulation results.

In press, Scripta Materialia, 2008 

DOI: 10.1016/j.scriptamat.2008.06.058

In a previous paper , we have demonstrated that a microcrystalline copper film well bonded to a polymer substrate can be stretched beyond 50% without cracking. The film eventually fails through the co-evolution of necking and debonding from the substrate. Here we report much lower strains to failure (around 10%) for polymer-supported nanocrystalline metal films, whose microstructure is revealed to be unstable under mechanical loading.

Zhigang Suo, Joost Vlassak, and Sigurd Wagner