Quasicrystalline phase formation in the mechanically alloyed Al70Cu20Fe10

Abstract

In the present work, the formation of the Al 70 Cu 20 Fe 10 icosahedral phase by mechanical alloying the elemental powders in a high-energy planetary mill was investigated by X-ray diffraction and Mössbauer spectroscopy. It was verified that the sample milled for 80 h produces an icosahedral phase besides Al(Cu, Fe) solid solution (β-phase) and Al 2 Cu intermetallic phase. The Mössbauer spectrum for this sample was fitted with a distribution of quadrupole splitting, a doublet and a sextet, revealing the presence of the icosahedral phase, β-phase and α-Fe, respectively. This compound is not a good hydrogen storage. The results of the X-ray diffraction and Mössbauer spectroscopy of the sample milled for 40 h and annealed at 623 • C for 16 h shows essentially single i-phase and tetragonal Al 7 Cu 2 Fe phase.Keywords Al-Cu-Fe quasicrystal · X-ray diffraction · Mössbauer spectroscopy and mechanical alloying

Rapid Solidification Processing and Bulk Metallic Glass Casting

“…Amorphous, quasicrystalline, and martensite are all metastable phases found in metal alloys as a result of solubility extension of the solute atoms at high cooling rates (47,59). Amorphous alloys are characterized by critical cooling rates, usually greater than 10 5 K s À1 and often have thickness less than 60 mm (60).…”

“…The quasicrystalline state is a metastable state between the amorphous and the crystalline phases with high mechanical properties such as hardness and stiffness (59,61). In contrast to the amorphous state, the quasicrystalline phase has a long-range rotational order but lacks a long-range translational order and is not truly periodic (59).…”