Sample-size effects in the yield behavior of nanocrystalline nickel

The compressive plastic strength of nanometer-scale single-crystal metallic pillars is larger than that found in conventionally sized samples. This behavior is generally associated with a change in the length scale that determines plastic behavior and the consequent inability of nanoscale samples to store dislocations. Here, we show in the case of nanocrystalline nickel pillars, for which there is a fixed microstructural length scale set by the grain size, that smaller is still stronger and find that this behavior derives from statistical expectations that have long been used to understand the size-dependent strength of brittle solids such as glass.