Is Smaller Stronger?

In 2004 researcher discovered that a single crystalline metal is stronger when the sample volume is reduced to the micron or even submicron range. In an ongoing debate on the origin of this phenomenon classical deformation theories are questioned. The suspicion that structural defects, i.e. deviations from perfect crystalline structure would play an important role in the smaller is stronger effect, could not be verified because of the lack of an appropriate measuring technique. In “Time resolved Laue diffraction of deforming micro pillars” the microstructure of micron sized Au pillars is followed in real time using a micro focused white X-ray beam at the microXAS beamline of the Swiss Light Source. This newly developed technique demonstrates the occurrence of crystal rotation and shows that the increased strength of the smallest Au pillars can be explained by plasticity starting on a slip system that is geometrically not predicted, but selected because of the character of the preexisting defect structure. Time resolved Laue diffraction presents itself as a powerful technique to investigate the fundamentals of the “smaller is stronger” paradigm.

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