Effect of solution heat treatment on the internal architecture and compressive strength of an AlMg4.7Si8 alloy

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 585; no. 100; pp. 480 - 487
• Main Authors: Tolnai, D., Requena, G., Cloetens, P., Lendvai, J., Degischer, H.P.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.11.2013; Elsevier; Elsevier Sequoia
• Subjects: 3D characterization; Al alloys; Applied sciences; Coarsening; Compressive strength; Curvature; Elasticity. Plasticity; Exact sciences and technology; High temperature; Intermetallics; Load transfer; Magnesium compounds; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Semiconductors; Silicides; Solution heat treatment; Synchrotron radiation computed tomography; Synchrotron radiation computed tomography; Al alloys; Coarsening; 3D characterization; Load transfer; Scanning electron microscopy; Statistical analysis; Morphological changes; Phase composition; Algae; Compressive strength; Compression test; Computerized tomography; Solution heat treatment; Eutectic; Microstructure; Curvature; Synchrotron radiation
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2013.06.033

The evolution of the microstructure of an AlMg4.7Si8 alloy is investigated by scanning electron microscopy and ex situ synchrotron tomography in as-cast condition and subsequent solution treatments for 1h and 25h at 540°C, respectively. The eutectic Mg2Si phase, which presents a highly interconnected structure in the as-cast condition, undergoes significant morphological changes during the solution heat treatment. Statistical analyses of the particle distribution, the sphericity, the mean curvatures and Gaussian curvatures describe the disintegration of the interconnected seaweed-like structure followed by the rounding of the disintegrated fractions of the eutectic branches quantitatively. The ternary eutectic Si resulting from the Si-surplus to the stoichiometric Mg2Si ratio of the alloy undergoes similar changes. The morphological evolution during solution heat treatment is correlated with results of elevated temperature compression tests at 300°C. The elevated temperature compressive strength is more sensitive to the degree of interconnectivity of the three dimensional Mg2Si network than to the shape of the individual particles.