Thermodynamic assessment of the Al-Ni system

Ansara, I.; Dupin, N.; Lukas, Hans Léo; Sundman, Bo

doi:10.1016/s0925-8388(96)02652-7

Cited by 487 publications

(215 citation statements)

References 34 publications

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“…L1 2 can be regarded as an ordered structure of Fcc_A1 and B2 as an ordered structure of Bcc_A2. In order to describe the potential second-order transition between an ordered structure and its disordered counterpart, the ordered and disordered structures have to be described with a single continuous Gibbs energy description [24,25] using the so-called partitioning model,…”

Section: Partitioning Modelmentioning

confidence: 99%

TCHEA1: A Thermodynamic Database Not Limited for “High Entropy” Alloys

Mao

Chen²,

Chen³

2017

J. Phase Equilib. Diffus.

125

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In this paper we report a thermodynamic database which was developed by using the CALPHAD approach. The TCHEA1 database includes 15 chemical elements (Al, Co, Cr, Cu, Fe, Hf, Mn, Mo, Nb, Ni, Ta, Ti, V, W and Zr). It is suitable for the study of Bcc and Fcc HEA systems. The database is constructed based on the thermodynamic assessment of all binary systems and many key ternary systems where almost all possible metastable and stable phases are considered. It is extensively demonstrated in the present work that TCHEA1 gives satisfactory prediction on the phase equilibria in various HEA systems (quaternary to ennead) and wide temperature ranges (liquidus to subsolidus). Thermodynamic stability calculations of simple solid solutions (Bcc and Fcc) and intermetallics (sigma, Laves, l-phase etc.) are validated against the available experimental information in as-cast or as-annealed state. Such CALPHAD database focusing on the modelling of Gibbs energy rather than entropy makes reliable predictions of thermodynamic equilibrium and phase transformation, no matter whether the alloy/system has high entropy or not. Cases with miscibility gap in liquid and solid solutions and second-order phase transition at low temperatures are demonstrated. With the volume data included, TCHEA1 is capable to predict the density and thermal expansion coefficient of HEAs as well. This thermodynamic database is also applicable in process simulations when used together with compatible kinetic databases.

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Section: Partitioning Modelmentioning

confidence: 99%

TCHEA1: A Thermodynamic Database Not Limited for “High Entropy” Alloys

Mao

Chen²,

Chen³

2017

J. Phase Equilib. Diffus.

125

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“…Thermodynamic models of the Ni-rich solid solutions have been published for all five binary alloy systems: Ni-Al [19][20][21], Ni-Ga [22], Ni-Ge [23], Ni-Si [24][25][26], and Ni-Ti [27]. There are also thermodynamic models of ternary Ni-rich solid solutions involving Al, Ga, Ge, Si, and Ti that are helpful in selecting data on G m [28][29][30][31][32][33].…”

Section: Recent Developmentsmentioning

confidence: 99%

“…For the alloys considered in this work the thermodynamic models involve at most four terms in the summations in Eq. (19). The equations for the derivatives in Cases 1 and 2 are therefore expressed as follows: Case 1:…”

Section: Curvatures Of the Free Energy Functionsmentioning

confidence: 99%

A1-L12 interfacial free energies from data on coarsening in five binary Ni alloys, informed by thermodynamic phase diagram assessments

Ardell

2011

J Mater Sci

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The data on coarsening of c 0 -type precipitates (Ni 3 X, with the L1 2 crystal structure) in Ni-Al, Ni-Ga, Ni-Ge, Ni-Si, and Ni-Ti alloys are re-evaluated in the context of recent (TIDC) and classical (LSW) theories of coarsening, with the objective of ascertaining the best values possible of interfacial free energies, r, of the c/c 0 interfaces in these five alloy systems. The re-evaluations include fitting of the particle size distributions, reanalyzing all the available data on the kinetics of particle growth and kinetics of solute depletion, and using thermodynamic assessments of the binary alloy phase diagrams to calculate curvatures of the Gibbs free energies of mixing. The product of the work is two sets of interfacial free energies, one set for the analysis using the recent TIDC theory and the other for the analysis using the classical LSW theory. The TIDC-based analysis yields lower values of r by about a factor of 2/3. All the interfacial energies are considerably larger, by factors ranging from *4 to 10, than those previously reported, which were for the most part calculated from data on coarsening assuming idealsolution thermodynamics. In the TIDC theory the width of the interface, d, is allowed to increase with particle size, r. A simple equation relating r to the ratio of the gradient energy and d is used to show that r can remain constant even though d increases with r. Published work supporting this contention is presented and discussed.

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“…To calculate M fromD; it is necessary to know the thermodynamic factor U. These were obtained using the formula U ¼ R g T G 00 mc (R g is the gas constant) after calculating G 00 mc using the procedures described in [37], which are based on the thermodynamic model of Ansara et al [86]. The vacancy wind factor, S, is ignored in these calculations.…”

Section: Relationship To Coarsening In Systems With Highly Disparate mentioning

confidence: 99%

Non-integer temporal exponents in trans-interface diffusion-controlled coarsening

Ardell

2016

J Mater Sci

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The kinetics of c 0 -type (Ni 3 X) precipitate growth and solute depletion in Ni-Al, Ni-Ga, Ni-Ge, Ni-Si, Ni-Ti and Ni-Al-Cr alloys is successfully predicted by the trans-interface diffusion-controlled theory of coarsening using non-integer temporal exponents, n, satisfying 2 B n B 3, which are obtained from analyses of particle size distributions (PSDs). The origin of non-integer n is concentrationdependent diffusion through the c/c 0 interface. The literature on diffusion of Al and Ni in Ni 3 Al is specifically examined. It is shown unequivocally that the concentration-dependent diffusion of Al can account semi-quantitatively for the value of n that successfully describes the PSDs and kinetics of coarsening of the c 0 precipitates. There is no need to invoke a particle size-dependent c/c 0 interface width, as was done in prior work. It is argued that existing theory and computational modeling of coarsening in systems with highly disparate diffusion mobilities in both phases do not correctly represent the mobilities in the matrix, precipitate, and interface in Ni-Al alloys. These theories predict temporal exponents satisfying 3 B n B 4, for which there is no experimental support.

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Thermodynamic assessment of the Al-Ni system

Cited by 487 publications

References 34 publications

TCHEA1: A Thermodynamic Database Not Limited for “High Entropy” Alloys

TCHEA1: A Thermodynamic Database Not Limited for “High Entropy” Alloys

A1-L12 interfacial free energies from data on coarsening in five binary Ni alloys, informed by thermodynamic phase diagram assessments

Non-integer temporal exponents in trans-interface diffusion-controlled coarsening

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