Al-Cu approximants in the alloy

Phase transformations and phase stability of the AlCuFe alloys with low-Fe content

“…However, from a comparison with the recently solved orthorhombic x 1 -Al 3 Cu 4 structure (aZ8.1267(3), bZ14.1985(5), and cZ9.9928(3), VolZ1153.0(1), space group Fmm2, ZZ4) of Gulay et al [24], whose cell corresponds to the facecentered orthorhombic (oF) cell (aZ8. 16(6), bZ14.14(9), and cZ9.99(5)) of Dong et al [23], an orthorhombic cell (space group Fmm2, aZ8.1530(3), bZ14.1370(4), and cZ 10.0736(4), VolZ1161.0(7), ZZ4 at room temperature) is found to approximate the observed pattern fairly well. The measured number of formula units (Al 10 Cu 10 Fe 1 ) of weight M r (relative molecular weight) per unit cell (ZZ4.1) and the calculated data (ZZ4) are corroboratory.…”

“…3(a) shows a series of high-temperature X-ray diffraction patterns for the Al 48.5 Cu 47.5 Fe 4.0 alloy, which was pre-annealed at 620 8C for 200 h. Based on the DTA and MTA measurements, this annealing at 620 8C caused the formation of the f-phase. A thorough comparison with powder diagrams generated from known structure models in the Al-Cu and the Al-Cu-Fe phase diagrams showed that the recently solved x 1 -Al 3 Cu 4 structure [24] which corresponds to the face-centered orthorhombic oF-phase of Dong et al [23], approximated the measured powder patterns at 463, 553 and 636 8C fairly well. However, this orthorhombic cell could not explain some weak reflections at low angles.…”

“…Since the phase diagram of the Al-Cu binary system in the composition range of 0.55!X cu !0.60 (at.%) is not yet completely clarified, the alloy compositions of AlCu, Al 2 Cu 3 and Al 3 Cu 4 were found to have at least two different types of structures depending on temperature (e.g. h 1 -AlCu with an orthorhombic cell [20], h 2 -AlCu with a monoclinic structure [21]; x 1 -Al 3 Cu 4, probably being orthorhombic [23,24], x 2 -Al 3 Cu 4 , probably being monoclinic [22]; and 3 1 -Al 2 Cu 3 , unknown structure, 3 2 -Al 2 Cu 3 with a hexagonal cell [18]). The structures of some phases are still unresolved, the ternary phases c and R have not yet been defined.…”

“…However, the exact crystallographic data such as space group, cell dimensions, and atomic coordination's of the f-Al 10 Cu 10 Fe are still unknown. Those of Al 2 Cu 3 [14][15][16]18] or Al 3 Cu 4 [23,24] were usually used Intermetallics 13 (2005) instead. The phase stability of the f-phase was investigated [5,8,9], and it was found to be stable below 650 8C.…”

Structurally complex metallic coatings in the Al-Cu system and their orientation relationships with an icosahedral quasicrystal

“…[1][2][3][4][5][6][7][8][9][10] This was motivated in part by the possibility of developing CMAs as new coating materials with low friction, reduced adhesion, and good corrosion resistance for technological applications. [11][12][13] Those surface properties are related to the peculiar electronic structure of CMAs characterized by a pseudogap at the Fermi level, usually associated with poor metallic behavior.…”