Relation Between Tensile Strut and Compressive Foam Deformation Behavior: Failure Mechanisms and the Influence of Dendritic Versus Globular Grain Structure in an AlSi7Mg0.3 (A356) Precision‐Cast Open‐Cell Foam

Advanced Engineering Materials, vol. 26

Abstract

Open‐cell aluminum foams are gaining importance for the design of lightweight structures and as electrodes in lithium‐ion batteries. AlSi7Mg0.3 foams are produced by a modified investment casting process. By tuning the mold temperature, a change from the usual nearly monocrystalline dendritic to a polycrystalline globular grain structure is achieved. Tension and compression tests on single struts and foam specimens, respectively, are combined with digital image correlation, scanning electron microscopy, and phase contrast‐enhanced microcomputed tomography in a synchrotron facility to correlate the mechanical properties and the failure mechanisms with the microstructure. The “globular” foams exhibit a lower strength and a less pronounced subsequent stress drop than the “dendritic” foams and the deformation mechanism changes from shear band‐dominated failure to a layer‐by‐layer collapse, because of the lower strength and higher ductility of the “globular” struts. The “dendritic” struts have a more homogeneous microstructure, while the “globular” struts often contain silicon agglomerates in their central region. Accordingly, the latter struts exhibit a higher degree of scatter for the fracture strain. Thus, the arrangement of the silicon particles and the eutectic determines the mechanical properties on the strut level and thereby the failure behavior on the foam level.

Authors 5

1. Aurélien Blond

   Technische Universität Berlin

   Affiliation as printed

   Fachgebiet Werkstofftechnik/Chair of Materials Science & Engineering, Institute of Materials Science and Technology, Faculty III Process Sciences Technische Universität Berlin Strasse des 17. Juni 135 Berlin 10623 Germany

2. Mahan Firoozbakht Aachen Foundry Institute

   RWTH Aachen University

   Affiliation as printed

   Foundry Institute RWTH Aachen University Intzestraße 5 Aachen 52072 Germany

3. Andreas Bührig–Polaczek Aachen Foundry Institute

   RWTH Aachen University

   Affiliation as printed

   Foundry Institute RWTH Aachen University Intzestraße 5 Aachen 52072 Germany

4. Ali Can Kaya corresponding

   Türkisch-Deutsche Universität

   Affiliation as printed

   Department of Mechatronics Engineering Turkish‐German University Sahinkaya, Caddesi 86, Beykoz Istanbul 34820 Turkey

   Department of Mechatronics Engineering, Turkish-German University, Sahinkaya, Caddesi 86, Beykoz, Istanbul, 34820 Turkey

5. Claudia Fleck corresponding

   Technische Universität Berlin

   Affiliation as printed

   Fachgebiet Werkstofftechnik/Chair of Materials Science & Engineering, Institute of Materials Science and Technology, Faculty III Process Sciences Technische Universität Berlin Strasse des 17. Juni 135 Berlin 10623 Germany