High temperature phase equilibria of the Ll2 composition in the AlTiNi, AlTiFe, and AlTiCu systems

Mazdiyasni, Siamack; Miracle, D.B.; Dimiduk, Dennis M.; Mendiratta, M. G.; Subramanian, P. R.

doi:10.1016/0036-9748(89)90376-1

Cited by 133 publications

(25 citation statements)

References 3 publications

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“…In the ternary Al-Ti-Fe system, however, the existence of A1 2 Ti is still a controversial topic. Markiv et al (1973) and Mazdiyasni et al (1989) identified AI 2 Ti in equilibrium with the L12 phase, but this conflicts with the work of Siebold (1981). Even in the work in which the AI 2 Ti was identified, detailed information, such as the solvus temperature, solubility of the ternary element, and the orientation relation between the AI 2 Ti and the L12 are not given.…”

Section: Ai 2 Ticontrasting

confidence: 52%

Plasticity of Single Crystalline Al3X Intermetallic Compounds

Luzzi¹,

Pope²,

Vitek³

1991

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Section: Ai 2 Ticontrasting

confidence: 52%

Plasticity of Single Crystalline Al3X Intermetallic Compounds

Luzzi¹,

Pope²,

Vitek³

1991

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“…The cubic phase t 3 with L1 2 structure is stable at compositions of 7.5 at.% Fe, 63.9e66.6 at.% Al and 28.6e25.8 at.% Ti, and no marked broadening of the single-phase field is observed with temperature between 800 and 1000 C [67]. Data available for 1200 C indicate that at this temperature t 3 is stable within a wider range of compositions [92]. Site preferences in t 3 and the long-range order parameter have been determined in Refs.…”

Section: Ternary Phasesmentioning

confidence: 80%

“…8 shows a sketch of the isothermal section at 1200 C based on the available experimental data. These data are from Mazdiyasni et al [92] for phase equilibria involving t 3 , Kainuma et al [72] and Tokar et al [98] for aTi þ bTi þ TiAl, hitherto unpublished studies by Ducher of aFe/TiAl diffusion couples of ternary AleFeeTi alloys and quinary alloys containing additional amounts of up to 0.5 at.% Nb þ Cr, and from Ducher et al [66] for the compositions of the liquid at the three-phase equilibria. These data are in good agreement with each other and also in accordance with the binary systems except for two points.…”

Section: Isothermal Sectionsmentioning

confidence: 83%

Assessment of the Al–Fe–Ti system

2006

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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.

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“…It is well known that addition of fourth-period transition elements including Cu to these intermetallics leads to the stability of the high-symmetry cubic L1 2 phase [2,12,[22][23][24][25][26][27][28][29][30][31][32][33][34][35]. These findings raise the intriguing possibility that such additions to Al-Ti-Zr alloys could give rise to the formation of a stable L1 2 precipitate microstructure.…”

Section: Introductionmentioning

confidence: 91%

“…The decrease in energy when Al resides in 4c and 4e sites relative to that in the 4d site is 14. 33 Figures 9(a) to 9(c), respectively. As seen in Figure 9(a), the relative stability of DO 23 , DO 22 and L1 2 phases is rather monotonic across the Al 3 Ti-Al 3 Zr section, and there is only a slight positive deviation from ideal (linear) behavior.…”

Section: Ab Initio Phase Stabilitymentioning

confidence: 99%

Final Report for Department of Energy Grant No. DE-FG02-02ER45997, "Alloy Design of Nanoscale Precipitation Strengthened Alloys: Design of a Heat Treatable Aluminum Alloy Useful to 400C"

Fine¹,

Ghosh²,

Isheim³

et al. 2006

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A creep resistant high temperature Al base alloy made by conventional processing procedures is the subject of this research. The Ni-based superalloys have volume fractions of cubic L1 2 phase precipitates near 50 %. This is not attainable with Al base alloys and the approach pursued in this research was to add L1 2 structured precipitates to the Al-Ni eutectic alloy, 2.7 at. % Ni -97.3 at. % Al. The eutectic reaction gives platelets of Al 3 Ni (DO 11 structure) in an almost pure Al matrix. The Al 3 Ni platelets give reinforcement strengthening while the L1 2 precipitates strengthen the Al alloy matrix. Based on prior research and the extensive research reported here modified cubic L1 2 Al 3 Zr is a candidate. While cubic Al 3 Zr is metastable, the stable phase is tetragonal, only cubic precipitates were observed after 1600 hrs at 425° C and they hardly coarsened at all with time at this temperature. Also addition of Ti retards the cubic to tetragonal transformation; however, a thermodynamically stable precipitate is desired. A very thorough ab initio computational investigation was done on the stability of L1 2 phases of composition, (Al,X) 3 (Zr,Ti) and the possible occurrence of tie lines between a stable L1 2 phase and the Al alloy terminal solid solution. Precipitation of cubic (Al (1-x) Zn x ) 3 Zr in Al was predicted by these computations and subsequently observed by experiment (TEM).To test the combined reinforcement-precipitation concept to obtain a creep resistant Al alloy, Zr and Ti were added to the Al-Ni eutectic alloy. Cubic L1 2 precipitates did form. The first and only Al-NiZr-Ti alloy tested for creep gave a steady state creep rate at 375° C of 8 X 10 -9 under 20MPa stress. The goal is to optimize this alloy and add Zn to achieve a thermodynamically stable precipitate.

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High temperature phase equilibria of the Ll2 composition in the AlTiNi, AlTiFe, and AlTiCu systems

Cited by 133 publications

References 3 publications

Plasticity of Single Crystalline Al3X Intermetallic Compounds

Plasticity of Single Crystalline Al3X Intermetallic Compounds

Assessment of the Al–Fe–Ti system

Final Report for Department of Energy Grant No. DE-FG02-02ER45997, "Alloy Design of Nanoscale Precipitation Strengthened Alloys: Design of a Heat Treatable Aluminum Alloy Useful to 400C"

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