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Main Title: Nanofatigue behaviour of single struts of cast A356.0 foam: cyclic deformation, nanoindent characteristics and sub-surface microstructure
Author(s): Schmahl, Merle
Märten, Anke
Zaslansky, P.
Fleck, Claudia
Type: Article
Abstract: Struts are the main load carrying elements in cyclically loaded open cell metal foams. Little is known about the local fatigue behaviour and the influence of the microstructure on nanoscale deformation mechanisms. Different to the bulk counterpart, the millimetre-sized struts in precision-cast AlSi7Mg0.3 foams contain only 1–2 Al-dendrites, Si-Al-eutectic and intermetallic phases. We applied cyclic nanoindentation to N = 105 to assess nanofatigue. The change in minimum depth per cycle and the ratio of minimum to maximum indentation depths versus the number of cycles correspond to cyclic plastic processes. These and the indent and pile-up morphologies were correlated with the microstructure and dislocation formations revealed by phase-contrast-enhanced micro-computed tomography and transmission electron microscopy. Our results reveal that Si-particles affect deformation within 5 to 10 μm from the indent, and that they favour the formation of fatigue induced dislocation cells in the affected volume. We believe that this interaction is mediated through residual stresses. Furthermore, local variations in microstructure strongly influence the cyclic deformation behaviour and the indent pile-up size and morphology. Interestingly, the results well coincide with observations during fatigue of the bulk alloy reported in the literature.
Subject(s): Al-Si-Mg alloy
open-cell metal foam
cyclic deformation behaviour
phase-contrast enhanced microcomputed tomography
transmission electron microscopy
indent morphology
Issue Date: 4-Aug-2020
Date Available: 1-Dec-2020
Language Code: en
DDC Class: 600 Technik, Technologie
Sponsor/Funder: DFG, 414044773, Open Access Publizieren 2019 - 2020 / Technische Universität Berlin
DFG, 73847914, SPP 1420: Biomimetic Materials Research: Functionality by Hierarchical Structuring of Materials
Journal Title: Materials & Design
Publisher: Elsevier
Volume: 195
Article Number: 109016
Publisher DOI: 10.1016/j.matdes.2020.109016
EISSN: 1873-4197
ISSN: 0264-1275
TU Affiliation(s): Fak. 3 Prozesswissenschaften » Inst. Werkstoffwissenschaften und -technologien » FG Werkstofftechnik
Appears in Collections:Technische Universität Berlin » Publications

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