Size effects in miniaturized polycrystalline FCC samples: Strengthening versus weakening

Abstract

This paper focuses on a computational-experimental analysis of sample geometry dominated and grain dominated size effects in miniaturized polycrystalline FCC components, where the grain size, orientation and grain boundaries play an important role. Experimental and numerical findings elucidate the joint contribution of first-order and second-order size effects for this type of components. The intrinsic competition between the weakening and strengthening contributions resulting from these effects is commented and further analysed. It is shown that a second-order crystal plasticity model is needed to account for the simultaneous contributions of both size effects.

Molecular Dynamics Simulation of Crack Propagation in Single-Crystal Aluminum Plate with Central Cracks

“…With the increase in the model size, the restriction of geometrically necessary dislocations on the statistical dislocations decreases, and the space and probability of the dislocation nucleation increase, which results in the decreased probability for local nonuniform plastic deformation. This result is consistent with the results of yield strength of material decreasing with model size as reported by Geers et al [31]. …”

Size and plasticity effects in zirconia micropillars compression

“…In these materials a combination of extrinsic and intrinsic length scales seems to affect the overall behavior. Different and conflicting deviations from the Hall-Petch relation have been found by independent studies in polycrystalline wires, sheets and micro-pillars of FCC metals [19]. In particular, in nanocrystalline Nickel it has been shown that the "smaller being stronger" trend can be inverted depending on the ratio thickness/grain size [20].…”

A three-dimensional dislocation field crystal plasticity approach applied to miniaturized structures

“…Inspired by the experimental results found in [22] and related comments in [28], two competing mechanisms that influence the size dependent behaviour are examined in detail, whereby the size of the grains in the microstructure is kept constant. As the dimensions of the structure diminish (accomplished by reducing the widths of the specimen), macroscopic deformation gradients are accentuated, while reversely, the deformation constraint imposed by the grain boundaries at adjacent grains decreases with decreasing dimensions.…”