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.

Energetic materials, such as solid propellants and high explosives, can be considered as composite materials with energetic particles embedded in polymeric binder matrix. These energetic materials display strong particle size effects. For example, large particles debond earlier than small ones in high explosives.