Regensburg 2019 – wissenschaftliches Programm
MM 28.3: Vortrag
Mittwoch, 3. April 2019, 15:45–16:00, H45
Micro & Nanomechanics of the Superplastic Alloy Zn-22% Al - Effect of Sample Size on Ductility — •Patrick Feldner, Mathias Göken, and Benoit Merle — Materials Science & Engineering, Institute I, Friedrich-Alexander-University Erlangen-Nuremberg, 91058 Erlangen, Germany
Superplastic micro & nanoforming has a great potential for a high throughput production of small-scale structural devices with complex geometries. However, it has not yet been established if the macroscopically observed superplastic behavior also persists at microscopic length scales and which fundamental processes govern structural superplasticity in metallic alloys. For this reason, the micro & nanomechanical properties of the superplastic alloy Zn-22% Al were characterized as a function of the specimen size, using nanoindentation at elevated temperatures, in situ pillar compression, as well as in situ tensile testing in a TEM. The measured local strain-rate sensitivity and apparent activation energy provided a strong evidence for superplastic like flow at the micrometer-scale. However, below a critical specimen volume a breakdown of the superplastic flow behavior is revealed, which is accompanied by a change of the apparent rate dependency. Based on the failure morphologies observed during in situ testing, this change of the rate-controlling deformation process is discussed in terms of a transition from boundary mediated ductility to boundary mediated brittleness.