Metastable quasicrystals in Al–Mn alloys containing copper, magnesium and silicon

• Published in: Journal of materials science Vol. 52; no. 23; pp. 13657 - 13668
• Main Authors: Naglič, Iztok, Samardžija, Zoran, Delijić, Kemal, Kobe, Spomenka, Dubois, Jean-Marie, Leskovar, Blaž, Markoli, Boštjan
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.12.2017; Springer; Springer Nature B.V
• Subjects: Alloys; Castings; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Composition; Copper; Copper compounds; Crystallography and Scattering Methods; Electron backscatter diffraction; Energy dispersive X ray spectroscopy; Icosahedral phase; Light diffraction; Magnesium; Magnesium castings; Manganese base alloys; Materials Science; Metals; Microscopy; Polymer Sciences; Quasicrystals; Scanning electron microscopy; Silicon; Solid Mechanics; Specialty metals industry; X-ray diffraction; X-ray spectroscopy; Electron Backscatter Diffraction Patterns (EBSDPs); Metastable QCs; Equal Mean Values; Copper Mold; Quasicrystals (QCs)
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-017-1477-8

We prepared three Al–Mn-based alloys with different copper, magnesium and silicon contents by casting into cylindrical copper molds. All the alloys exhibited primary metastable quasicrystals (QCs). In order to confirm the presence of either primary decagonal QCs (dQCs) or icosahedral QCs (iQCs) and to determine their compositions, the castings were characterized by means of light microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDS), electron-backscatter diffraction and X-ray diffraction. The dQCs are present in the Al–Mn-based alloys containing copper. In the case of the combined presence of copper and magnesium, iQCs are present in the edge region and dQCs are present in the central region. In the alloy containing copper, magnesium and silicon, iQCs are present in the casting. The average metallic radius (AMR) and electron-to-atom ratio of these primary phases were calculated by taking into account the composition of these primary phases, as determined by EDS. The AMR shows different values in the cases of dQCs and iQCs. Equal mean values of the AMR were found in iQCs with markedly different compositions. Furthermore, all the metastable QCs in this work show electron concentrations close to 2.6.