The phase equilibria of N3Al evaluated by directional solidification and diffusion couple experiments

Verhoeven, J. D.; Lee, J. H.; Laabs, F. C.; Jones, Laurence

doi:10.1007/bf02663666

Cited by 53 publications

(12 citation statements)

References 5 publications

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“…The magnification shows the calculated diagram phase in the region of the invariant equilibria involving the gø and liquid phases. There is a peritectic reaction on the Ni side and an eutectic one with AlNi, in agreement with the more recent studies [25][26][27]. The nature of these invariant reactions can be considered not important in a thermodynamic point of view because there is little energetic difference between this case and the one where the liquidπgπgø forms a eutectic reaction.…”

Section: Assessed Systemssupporting

confidence: 89%

A thermodynamic database for Ni‐base superalloys

Dupin

Sundman

2001

Scand Jof Metallurgy

101

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A thermodynamic database has been developed for Ni‐base superalloys. Following the CALPHAD procedure, it is based on the assessment of thermodynamic behaviour of the relevant constituting sub‐systems of the complex system of interest. The current database contains 7 elements: Al, Co, Cr, Ni, Ti, W, Re. The thermodynamics of the γ and γ′ phases are modelled with a single Gibbs energy function taking into account the crystallographic relation between these two phases. The formalism of the thermodynamic models used is briefly introduced. A few phase diagrams calculated with the current database in assessed binary and ternary systems are presented. Some experiments available in higher order systems are compared with the results of calculations with the current database. The ability of extrapolation of the database is verified for solid state equilibria as well as for solidification behaviour (liquidus temperature and partition ratios). The introduction of Mo and Ta to the current database is in progress. Other elements (Nb, Fe, Zr, Hf, C, B, ···) are planed to be introduced.

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Section: Assessed Systemssupporting

confidence: 89%

A thermodynamic database for Ni‐base superalloys

Dupin

Sundman

2001

Scand Jof Metallurgy

101

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“…The binary systems Al±Ni and Ni±Ti were essentially accepted in the version given in Massalski [9] with modi®cation of the solidi®cation behaviour of AlNi 3 after Verhoeven [10]. Al±Ti was used in the form presented in [11,12].…”

Section: Binary Systemsmentioning

confidence: 99%

The ternary system Al–Ni–Ti Part I: Isothermal section at 900°C; Experimental investigation and thermodynamic calculation

et al. 1999

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Phase relations in the ternary system Al±Ni±Ti have been experimentally established for the isothermal section at 900 C for concentrations 0.1 4 x Al 4 0.7. The investigation is based on X-ray powder diraction, metallography, SEM and EMPA-techniques on about 40 ternary alloys, prepared by argon-arc or vacuum-electron beam melting of proper elemental powder blends. The existence of four ternary compounds, t 1 to t 4 , is con®rmed, however, in contrast to earlier investigations at signi®cantly dierent compositions and with dierent shape of the homogeneity regions. This is particularly true for the phase regions of t 3-Al 3 NiTi 2 with the MgZn 2-type structure ranging from Al 30 Ni 28 Ti 42 (composition lowest in Al) to Al 50 Ni 16 Ti 34 (composition richest in Al) and for t 2-Al 2 NiTi. The complex atom site substitution mechanism in t 3 changing from Ti/Al exchange at Al-poor compositions towards Ni/Al replacement for the Al-rich part was monitored in detail by quantitative X-ray powder diraction techniques (Rietveld analyses). In contrast to earlier reports, claiming a two-phase region Ni{Al x Ti 1-x } 2 +t 3 , we observed two closely adjoining three-phase equilibria: a 2-AlTi 3 +Ni{Al x Ti 1-x } 2 + t 4-AlNi 2 Ti and a 2-AlTi 3 +t 3-Al 2 NiTi 2 +t 4-AlNi 2 Ti. The earlier reported ``homogeneous phase at Al 23 Ni 26 Ti 51 H '' was shown by high resolution microprobe and X-ray diraction measurements to be an extremely ®negrained eutectic. The experimental results are in ®ne agreement with the thermodynamic calculation.

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“…4. The calculated Ni-Al binary phase diagram is compared with the experimental data [24][25][26]28,[38][39][40][41][42] in Fig. 5.…”

Section: Ni-al Binary Systemmentioning

confidence: 99%

Phase Separation of the B2 Structure Accompanied by an Ordering in Co-Al and Ni-Al Binary Systems

2004

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The phase separation of the B2 structure in the Co-Al and Ni-Al binary systems has been studied by combining ab initio energetic calculations with the CALPHAD approach. The total energies of the ordered phases based on the bcc lattice were obtained using first-principle band-energy calculations. The cluster expansion method was applied to the results, and the free energies at finite temperatures were calculated for the bcc solid solution. The Co-Al and Ni-Al binary systems were analysed thermodynamically by considering the estimated metastable free energy of the bcc phase. The descriptions of the lattice stability parameters for each pure element were obtained chiefly from the Scientific Group Thermodata Europe (SGTE) datafile. The optimized parameters reasonably reproduced the characteristic features of these binary phase diagrams. The metastable (A2+B2) two-phase field forms in the Co-Al phase diagram, and this equilibrium is closely related to the anomaly in the phase boundaries of the binary system. On the other hand, the phase separation of the A2 and B2 structures are hindered by the presence of the D0 3 phase in the Ni-Al system. Ground state analysis was performed to clarify the difference in the behaviour of the B2 phase.

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The phase equilibria of N3Al evaluated by directional solidification and diffusion couple experiments

Cited by 53 publications

References 5 publications

A thermodynamic database for Ni‐base superalloys

A thermodynamic database for Ni‐base superalloys

The ternary system Al–Ni–Ti Part I: Isothermal section at 900°C; Experimental investigation and thermodynamic calculation

Phase Separation of the B2 Structure Accompanied by an Ordering in Co-Al and Ni-Al Binary Systems

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