On the relationship between surface roughness evolution and size effects in free-standing Cu films with fine microstructure

摘要

In situ surface roughness measurements are used to elucidate size effects on plastic deformation mechanisms in free-standing Cu films with a fine microstructure. Spectral analysis of the surface roughness distribution showed the competing influences of micro-structure- and free surface-induced effects on strength and ductility. The measurements show that the free-surface effect on inter-granular interactions underlies the reduction in strength and ductility seen with thickness reduction. We find that while microstructure refinement increases film strength, it also serves to limit ductility.