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MM: Fachverband Metall- und Materialphysik
MM 14: Topical session: Interface-Controlled Microstructures: Mechanical Properties and Mechano-Chemical Coupling - Electro- and mechno-chemical coupling
MM 14.5: Vortrag
Montag, 20. März 2017, 16:45–17:00, BAR 205
Electrical modulation of the Poisson’s ratio of nanoporous metals — •Lukas Lührs1, Birthe Müller1, and Jörg Weissmüller1,2 — 1Institute of Materials Physics and Technology, Hamburg University of Technology — 2Institute of Materials Research, Materials Mechanics, Helmholtz-Zentrum Geesthacht
Nanoporous metals exhibit significant surface induced property modifications that are rendered possible by their large surface area to volume ratio. Among these materials nanoporous gold (NPG) appears an ideal model material due its high chemical stability and tunable surface area. Owing to its decisive electro mechanical coupling, electrical modulation of the strength and flow stress, elastic modulus, creep behavior and crack propagation have been demonstrated. However, the reliance of the lateral deformation behavior of NPG towards electrical tuning remains unclear.
In this contribution we study the influence of electrical modulation on the transverse mechanical coupling of NPG by the investigation of a metal/electrolyte hybrid material. We present experiments of NPG under compression testing in 1 M HClO4 while varying the applied electrical potential, E. Our results show considerable changes of the plastic Poisson’s ratio, νP, with E. We link these findings to the surface tension, γ, a capillary force that promotes a tension/compression asymmetry in the material. As γ depends on E, we show that the plastic lateral expansion behavior is governed by surface effects. In this line of argument we interpret the earlier reported ligament size dependence of νP.