2015-Sustainable Industrial Processing Summit
SIPS 2015 Volume 1: Aifantis Intl. Symp. / Multiscale Material Mechanics
| Editors: | Kongoli F, Bordas S, Estrin Y |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2015 |
| Pages: | 300 pages |
| ISBN: | 978-1-987820-24-9 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Intrinsic and Extrinsic Size-effects in Metallic Systems
Jeff DeHosson1;1UN. OF GRONINGEN, Groningen, Netherlands;
Type of Paper: Regular
Id Paper: 135
Topic: 1
Abstract:
In the field of transmission electron microscopy fundamental and practical reasons still remain that hamper a straightforward correlation between microscopic structural information and deformation mechanisms in materials. We argue that one should focus in particular on in-situ rather than on postmortem observations of the microstructure. In this contribution, this viewpoint will be exemplified with in-situ TEM nanoindentation and in-situ straining studies on crystalline and non-crystalline metallic materials. In-situ TEM displacement-controlled indentations in crystalline alloys show that many dislocations are nucleated prior to the initial macroscopic yield point and that the macroscopic yield event is associated with the rearrangements of the dislocations. Also size effect, or the lack thereof, during deformation of nano-sized metallic glasses (MGs) has recently drawn great attention. An intriguing question is why and how nucleation and propagation of these shear bands (SBs) are affected by the size of the system. Therefore, we have carried out quantitative in-situ TEM deformations of metallic glass pillars with diameters ranging from 50 nm to 500 nm. A micromechanical model based on quantitative description of shear banding events explains the size-dependent deformation behavior and a statistical analysis of strength reveals the physical picture defined by the interactions between stress fields of flow defects. Implications of our findings for applications in nanosized systems will be illustrated.