Multi length-scale characterisation of microstructure/geometry interactions for tailoring properties of open-cell Al alloy foams
Final Report Abstract
The project aimed to enhance the production, microstructure control, and mechanical properties of aluminum-based foams and lattice structures for lightweight structural applications in industries like automotive and aerospace. The effects of casting parameters, such as mold and melt temperatures, on AlSi7Mg foams were studied. Higher mold temperatures improved mold filling but led to brittle fracture due to large silicon particles and dendritic aluminum grains. Lower mold temperatures promoted globular aluminum structure and homogeneous silicon distribution, improving ductility and energy absorption. Adding strontium (Sr) to modify the silicon phase showed improved mechanical properties and reduced stress-strain fluctuations, though excess Sr (800 ppm) reduced properties. Heat treatment (precipitation hardening) of Al-3.8%Cu and Al-4.8%Cu foams significantly increased tensile strength and hardness, with smaller precipitates enhancing strength and larger ones reducing ductility. Heat treatment (T6 strengthening) of A356 foams increased hardness and plateau stress, improving mechanical properties by up to 60%. Integrating 3D-printed patterns into the casting process allowed for creating complex lattice structures (BCC, Diamond, and Kelvin), where improved ductility and processing methods reduced peak stresses and improved energy absorption. The results highlight the importance of controlling casting parameters, alloy composition, and post-processing to adapt the mechanical behavior and energy absorption of aluminum foams and lattice structures to defined boundary conditions.
Publications
-
Modification of iron intermetallic from beta phase to Chinese script phases in the ultrathin cast aluminum foams, SME Congress, Darmstadt, Topic of Accompanying and Unusual Elements in Aluminum and its Alloys.
M. Firoozbakht, A.C. Kaya, A. Blond, C. Fleck & A. Bührig-Polaczek
-
Analyzing the influence of the investment casting process parameters on microstructure and mechanical properties of open-pore Al–7Si foams. Journal of Materials Research and Technology, 23, 2123-2135.
Firoozbakht, Mahan; Blond, Aurélien; Zimmermann, Golo; Kaya, Ali Can; Fleck, Claudia & Bührig-Polaczek, Andreas
-
Proactive, Innovative, and Flexible Foundry Institute: Review of Investment Casting Researches, 63rd IFC Congress, Portoroz.
M. Firoozbakht & A. Bührig-Polaczek
-
Study of the Solidification Behavior and Homogenization Heat Treatment of the Investment-Cast Al–Cu Foams: Experimental and Modelling Investigations. The Minerals, Metals & Materials Series, 627-634. Springer Nature Switzerland.
Mohammed, Waleed; Firoozbakht, Mahan & Bührig–Polaczek, Andreas
-
Modification of open-cell cast aluminum-silicon foams with strontium. Journal of Alloys and Compounds, 1002, 175426.
Firoozbakht, Mahan; Blond, Aurélien; Fleck, Claudia; Kaya, Ali Can & Bührig-Polaczek, Andreas
-
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, 26(15).
Blond, Aurélien; Firoozbakht, Mahan; Bührig‐Polaczek, Andreas; Kaya, Ali Can & Fleck, Claudia
-
Characterization of the Deformation Behavior of Aluminum Alloy Lattice Structures Produced by Hybrid Investment Casting. InCeight Casting Congress 05-06 March 2025, Darmstadt
M. Firoozbakht, A.C. Kaya, A. Blond, C. Fleck & A. Bührig-Polaczek
-
Deformation Behavior of Aluminum Alloy Lattice Structures Produced by Hybrid Investment Casting, InCeight Casting Congress, Darmstadt.
M. Firoozbakht & A. Bührig-Polaczek
-
From nano to macro: understanding the microstructural interactions for influencing the mechanical properties of open-cell Al alloy foams, Doctoral thesis, TU Berlin
Aurélien Blond
