An investigation of the Al–Pd–Fe phase diagram between 50 and 100 at.% Al: phase equilibria at 750 °C

Abstract

The isothermal 750 • C section of Al-Pd-Fe was determined between 50 and 100 at.% Al. The range of the Al-Pd orthorhombic ε-phases extends up to ∼10 at.% Fe. Apart from the four specific structural variants ε 6 , ε 16 , ε 22 and ε 28 , irregular structures were observed in this continuous range. In addition to the ternary cubic C 1 , C 2 phases and orthorhombic O-Al 13 (Fe,Pd) 4 observed at higher temperatures, a new stable orthorhombic N-phase was revealed. It exhibits a structural relation to the ε-phases and decagonal quasicrystals.

Decagonal quasicrystals in Al–Pd–Fe

“…In Fig. 3 the powder XRD patterns of the relevant Al-Pd-Fe phases [7] are compared to that of the Al-Ni-Ru D-phase [8]. We expect the powder pattern of the Al-Pd-Fe D-phase to be qualitatively similar to that in Al-Ni-Ru since both have similar Al concentration and the proportion between Ni and Ru is quite close to that between Fe and Pd.…”

“…In a solidified sample of Al 76.7 Pd 15.6 Fe 7.7 a phase of similar composition was observed mainly around the O-Al 13 (Fe,Pd) 4 phase grains. However, in a more recent work, which was carried out at lower temperatures [7], this observation was attributed to the formation of a periodic so-called N-phase and not related to the formation of the above-mentioned phase mixture. Again, no stable decagonal phase was observed.…”

“…The 3-phase is extended from Al-Pd and exhibits a number of orthorhombic structural variants depending on the composition [7,9]. At its high-Fe end it has the 3 16 -structure [5][6][7]. There are also the ternary cubic C-phase and the orthorhombic N-and O-Al 13 (Fe,Pd) 4 phases.…”

“…There are also the ternary cubic C-phase and the orthorhombic N-and O-Al 13 (Fe,Pd) 4 phases. Their crystallographic data [5][6][7] and maximal melting temperatures are presented in Table 1. The electron diffraction patterns of the 3, N and O phases taken along the [010] direction are similar to that of a decagonal quasicrystal taken along the tenfold direction [6,7].…”

Physical properties of the complex metallic alloy phases in the Al–Pd–Mn system

“…Among the CMA materials, an interesting family of related structures was revealed in the Al-Pd alloys system [3,4] and its ternaries with transition metals (Mn, Fe, Co, Rh) [5][6][7][8][9]. The simplest regular structure discovered first in the Al-Pd-Mn [5,6] system, designated as ξ', contains 320 atoms in its orthorhombic unit cell.…”