Sample Dimensions Influence Strength and Crystal Plasticity

TLDR

When a crystal deforms plastically, phenomena such as dislocation storage, multiplication, motion, pinning, and nucleation occur over the submicron-to-nanometer scale. The study reports measurements of plastic yielding in micrometer‑sized single crystals of three different metals. The authors measured plastic yielding in these micrometer‑sized single crystals. The results show that overall sample dimensions artificially limit the length scales available for plastic processes, producing dramatic size effects even at surprisingly large dimensions, and emphasize that both external geometry and internal structure must be defined to characterize material strength at the micrometer scale.

Abstract

When a crystal deforms plastically, phenomena such as dislocation storage, multiplication, motion, pinning, and nucleation occur over the submicron-to-nanometer scale. Here we report measurements of plastic yielding for single crystals of micrometer-sized dimensions for three different types of metals. We find that within the tests, the overall sample dimensions artificially limit the length scales available for plastic processes. The results show dramatic size effects at surprisingly large sample dimensions. These results emphasize that at the micrometer scale, one must define both the external geometry and internal structure to characterize the strength of a material.