Microstructural and mechanical characterization of quasicrystalline Al-Cu-Fe foams

Quasi-crystalline metal foams are considered a new class of materials, as they differ fundamentally from conventional materials in their atomic structure and mechanical properties. Their manufacturing methods are under constant development. In this article, the microstructural characterization and the mechanical behavior of quasicrystalline foams obtained via slow solidification and heat treatment with the presence of molten metal is presented. The studied Al₆₃Cu₂₈Fe₉ alloy was thermally treated at 800 °C for short times from 5 to 15 min and for longer times of 180 and 360 min in order to promote the formation of a metal structure constituted by icosahedral phase with a high percentage of porosity. The microstructural characterization was performed by using the X-ray diffraction (XRD) technique, scanning electron microscopy (SEM) and optical microscopy (OM). The thermal properties of the as-cast alloy and the changes in the density of the thermally treated samples were characterized by a differential thermal analysis (DTA) and Archimedes method, respectively. The highest percentage of macroporosity (40%) was obtained in the heat-treated sample at 800 °C for 360 min. Under these heat treatment conditions, a completely porous structure (foam) mainly constituted by quasicrystalline icosahedral phase was formed. The maximum compressive stress value and average plateau stress reached for the alloy heat-treated during 360 min were 80 MPa and 30 MPa, respectively.