The role of the Φ phase in the solidification process of Al–Cu–Fe icosahedral quasicrystal

• Published in: Materials letters Vol. 57; no. 29; pp. 4493 - 4500
• Main Authors: Zhao, Dongshan, Wang, Renhui, Wang, Jianbo, Qu, Wenbang, Shen, Ningfu, Gui, Jianian
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.11.2003; Elsevier
• Subjects: Alloys; Condensed matter: structure, mechanical and thermal properties; Crystal structure; Electron microscopy; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Icosahedral quasicrystal phase; Microstructure; Physics; Polythermal projection; Solid-solid transitions; Solidification; Specific phase transitions; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Icosahedral quasicrystal phase; Microstructure; Electron microscopy; Crystal structure; Solidification; Polythermal projection; Scanning electron microscopy; Ternary alloys; Iron alloys; XRD; Experimental study; Quasicrystals; Icosahedral phase; Transmission electron microscopy; Aluminium alloys; Copper alloys; Modulation; Chemical composition; Transition element alloys
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/S0167-577X(03)00349-5

Several Al–Cu–Fe alloys with compositions of Al 48–60Cu 33–50Fe 0–10 was prepared and the phase constituents of these alloys quenched from various temperatures were identified by using X-ray diffraction (XRD), differential thermal analysis (DTA), SEM with dispersive X-ray spectrometer (EDXS) attached to, and transmission electron microscopy (TEM) (including HRTEM). The present investigation confirmed again the existence of the Φ phase with a chemical composition of Al 10Cu 10Fe, having two variants. The high temperature variant (designated as Φ 1 phase) is stable when temperature is higher than nearly 600 °C and has a structure of τ 3 phase, which is a three-time modulation structure along a 〈111〉 B2 direction. The low temperature variant (designated as Φ 2 phase) is stable when temperature is lower than nearly 500 °C and has a 10-time modulation structure along a 〈011〉 B2 direction. We show the preferred polythermal projection and reaction scheme. Compared with the suggestion proposed by Gayle et al. [Metall. Trans., A 23A (1992) 2409.], Faudot [Ann. Chim. Fr. 18 (1993) 445.], and Zhang and Lueck [J. Alloys Compd. 343 (2002) 53.], the main amendment is to divide the previous β region into β+Φ two regions. The important reactions of the Φ phase involving the icosahedral quasicrystal (IQC) are (1) quasiperitectic at U 8: L+β→Φ+IQC; (2) quasiperitectic at U 5: L+IQC→Φ+ω; (3) peritectic (between U 8 and U 5): L+IQC→Φ.