Effects of Film Thickness on the Yielding Behavior of Polycrystalline Gold Films

A Membrane Deflection Experiment was used to test the mechanical response of freestanding thin film gold specimens. We present stress-strain curves obtained on films 0.3, 0.5 and 1.0 μm thick. Elastic modulus was consistently measured in the range of 53-55 GPa. Several size effects on the mechanical properties were observed including yield stress variations with membrane width and film thickness. It was observed that thickness plays a key role in deformation behavior with a major transition in the material inelastic response occurring between a thickness of 0.5 and 1.0 μm. The size effects here reported are the first of their kind in the sense that the measurements were performed under a macroscopically homogeneous axial deformation, i.e., in the absence of macroscopic deformation gradients.