Enhanced yield strength of materials: The thinness effect

We show that yield strength is determined by "thinness" i.e., by the smallest dimension of a structure. Compressing wall-like structures of different length to width ratio, using a NanoindenterXP, has allowed us to distinguish between proposed plasticity size effect theories by determining the dimensional dependence of uniaxial plastic deformation of small pillars. We show that yield stress is determined by wall width; the length of the wall making little or no difference. Thus thin structures exhibit the same enhanced yield strength regardless of total size (volume) or surface to volume ratio; nanolayers are as strong as nanoparticles. (C) 2009 American Institute of Physics. [doi:10.1063/1.3226106]