Assessment of the Al–Fe–Ti system

Abstract

The Al-Fe-Ti system has been assessed and the limiting binary systems are shortly reviewed.Based on a thorough review of the literature, isotherms at 800, 900, and 1000 °C have been re-evaluated and a provisional isotherm at 1200 °C is presented for the first time. The effect of alloying the binary phases with the third component is reviewed with regard to the ternary homogeneity ranges, crystallography, order/disorder transformations, and site occupancies. Of the variously reported ternary compounds only the existence of "Al 2 FeTi" (τ 2 ) and "Al 8 FeTi 3 " (τ 3 ) is confirmed. The occurrence of the phases τ 2 * , τ′ 2 , and of a new stacking variant of TiAl is still under discussion, while the existence of the phases Fe 2 AlTi (τ 1 ) and Fe 25 Al 69 Ti 6 (X) is ruled out. The presented reaction scheme corroborates the isothermal sections and also a representation of the liquidus surface is given. Magnetic, electrical, thermochemical, atomistic and diffusion data for Al-Fe-Ti alloys are summarised and an overview about studies on modelling of phase equilibria and phase transformations is given.

The Heusler Phase Ti25(Fe50 − x Ni x )Al25 (0 ≤ x ≤ 50); Structure and Constitution

“…Compositions of phases in the TiFe 2 Al alloy after ND and after annealing at various temperatures between 800 and 1200°C have been measured on a Cameca SX 50 and a Jeol JXA-8100 at 15 kV and 20 nA using the pure elements as standards. [44,45] For 1000°C a similar phase constitution was found by Fu et al [41] in this alloy series. Lattice parameters a as a function of Ni content (x) are plotted in Fig.…”

Phase Separation from L2<SUB>1</SUB> to (B2+L2<SUB>1</SUB>) in Fe-24.6Al-7.5Ti Alloy

“…In previous studies, [1][2][3][4][5][6][7][8][9][10][11] it is seen that the Ti addition in the Fe-Al binary alloys would (1) strongly increase the D0 3 !B2 and B2!A2 transition temperatures, [1][2][3][4][5][6][7][8][9][10] (2) significantly expand the (A2+D0 3 ) phase field, [5][6][7] and (3) cause the D0 3 APBs to exhibit a tendency toward anisotropy. 6) In addition, a (B2+L2 1 ) (L2 1 is the ternary equivalent of the binary D0 3 structure.…”

“…3) ) two-phase field was reported to be existent at temperatures ranging from 1073 to 1273 K in the Fe-Al-Ti ternary alloys. [7][8][9][10][11] It is noted that the (B2+D0 3 ) two-phase field has not been found by previous workers in the Fe-Al binary alloys before. 12,13) However, the existence of the (B2+L2 1 ) two-phase field in the Fe-Al-Ti ternary alloys was determined principally by using X-ray diffraction, differential scanning calorimetry, differential thermal analysis and electron-probe microanalysis.…”

“…12,13) However, the existence of the (B2+L2 1 ) two-phase field in the Fe-Al-Ti ternary alloys was determined principally by using X-ray diffraction, differential scanning calorimetry, differential thermal analysis and electron-probe microanalysis. [7][8][9][10][11] Recently, we have performed transmission electron microscopy (TEM) investigations on the phase transformations of a Fe-23 at% Al-8.5 at% Ti alloy aged at 1173 K. 14) Consequently, it was found that when the alloy was aged at 1173 K for longer times, the L2 1 domains grew considerably and an A2! (A2+L2 1 )!…”

Formation of (B2+D0<SUB>3</SUB>) Two-Phase Microstructure in a Fe-23 Al-7 Ti Alloy

“…[1][2][3][4][5][6][7][8][9] Based on these studies, it can be generally concluded that the addition of Ti in the Fe-Al binary alloys would not only pronouncedly raise the A2+D0 3 (or D0 3 ) ! B2 !…”