Size effects in thin coarse-grained gold microwires under tensile and torsional loading

Deformation patterns in cross-sections of twisted bamboo-structured Au microwires

“…When viewing the results of the present investigations it is clearly seen, that Laue microdiffraction, supported by CP simulations, is generally an excellent tool to determine both the global and local deformation behavior within twisted microspecimenat least for (pseudo) single crystalline metals. Based on both well selected samples and statistical analyses, the method can be used to study general aspects of deformation in torsion beyond yielding, as well as to clarify specific aspects, for example concerning the physical background of already observed size effects [1,12,17].…”

“…Given by limitations of current manufacturing techniques, long metallic wires are naturally polycrystalline. To account for this, special emphasis has been given to the ratio of grain size and wire diameter and thereby it is proposed that the observed size effects are related to both, the relevant microstructural length scale (grain size, dislocation density) and the sample size [14][15][16][17]. However, the interplay of the different length scales, particularly in combination with imposed strain gradients in torsion, is not known as their individual contribution to the overall size effects could not be quantified up to now [17].…”

“…To account for this, special emphasis has been given to the ratio of grain size and wire diameter and thereby it is proposed that the observed size effects are related to both, the relevant microstructural length scale (grain size, dislocation density) and the sample size [14][15][16][17]. However, the interplay of the different length scales, particularly in combination with imposed strain gradients in torsion, is not known as their individual contribution to the overall size effects could not be quantified up to now [17]. Consequently, it is indeed questionable if the assumptions of the classical strain gradient theories with respect to strain distribution and accumulation of GNDs may hold for polycrystalline microstructures and if it is reasonable to apply them to describe torsion experiments of polycrystalline wires.…”

Accounting for the recoverable plasticity and size effect in the cyclic torsion of thin metallic wires using strain gradient plasticity

“…To date, we have performed comprehensive works on torsion experiments of thin metallic wires by using a novel torsion balance technique [4,[16][17][18]. Related works by other researchers in this field are also on-going [19][20][21][22][23][24][25]. For example, Dunstan and Bushby [20] developed a micro-torsion technique based on the load-unload technique [26] for micrometer-dimensioned wires.…”

Review on slip transmission criteria in experiments and crystal plasticity models

“…For large-grained microstructures [49], the GB modeling is of utmost importance since the GB presence and influence on the dislocation movement leads to pile-ups of dislocations that can, in turn, dominate the material behavior. Associated occurring phenomena are size effects, e.g., [71,72]. Size effects can be modeled in gradient plasticity models by different approaches.…”