SKM 2021 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 3: Topical Session Interface-Dominated Phenomena - Defect Structures and Mechanical Properties

MM 3.1: Vortrag

Montag, 27. September 2021, 13:30–13:45, H2

Imaging the Deformation-Induced Accumulation of Defects in Nanoporous Gold — •Maowen Liu¹ and Jörg Weissmüller^{1, 2} — ¹Institute of Materials Physics and Technology, Hamburg University of Technology — ²Institute of Materials Research, Materials Mechanics, Helmholtz-Zentrum Hereon

Nanoporous gold (NPG) provides a model material for studying small-scale deformation and the mechanical behavior of network solids. While studies of nanopillars indicate dislocation starvation, the strain hardening of NPG suggests dislocation accumulation. Yet, the approach to confirm that latter process by direct experimental observation, namely transmission electron microscopy (TEM), is impaired by the need to distinguish native defects in the microstructure from artifacts due to sample slicing or thinning. Here, we report a TEM study of the defect structure in electron-transparent NPG leaf deformed by rolling. The results confirm that plastic deformation significantly enhances the defect density. Specifically, twins are formed on several crystallographic planes, and their interaction forms Lomer-Cottrell locks. This inhibits dislocation escaping from NPG, thus avoiding the dislocation starvation scenario that is often considered in the "smaller is stronger" context of small-scale plasticity. Instead, strain-hardening is apparently linked to accumulation and interaction of twins.