scholarly journals About the Reliability of CALPHAD Predictions in Multicomponent Systems

Entropy ◽  
2018 ◽  
Vol 20 (12) ◽  
pp. 899 ◽  
Author(s):  
Stéphane Gorsse ◽  
Oleg Senkov
Keyword(s):  
Phase Space ◽  
Thermodynamic Properties ◽  
Binary Systems ◽  
Thermodynamic Description ◽  
Quaternary Alloy ◽  
Intermetallic Phases ◽  
Phase Boundaries ◽  
High Entropy ◽  
Quaternary Phase ◽  
Alloy Systems

This study examines one of the limitations of CALPHAD databases when applied to high entropy alloys and complex concentrated alloys. We estimate the level of the thermodynamic description, which is still sufficient to correctly predict thermodynamic properties of quaternary alloy systems, by comparing the results of CALPHAD calculations where quaternary phase space is extrapolated from binary descriptions to those resulting from complete binary and ternary interaction descriptions. Our analysis has shown that the thermodynamic properties of a quaternary alloy can be correctly predicted by direct extrapolation from the respective fully assessed binary systems (i.e., without ternary descriptions) only when (i) the binary miscibility gaps are not present, (ii) binary intermetallic phases are not present or present in a few quantities (i.e., when the system has low density of phase boundaries), and (iii) ternary intermetallic phases are not present. Because the locations of the phase boundaries and possibility of formation of ternary phases are not known when evaluating novel composition space, a higher credibility database is still preferable, while the calculations using lower credibility databases may be questionable and require additional experimental verification. We estimate the level of the thermodynamic description which would be still sufficient to correctly predict thermodynamic properties of quaternary alloy systems. The main factors affecting the accuracy of the thermodynamic predictions in quaternary alloys are identified by comparing the results of CALPHAD calculations where quaternary phase space is extrapolated from binary descriptions to those resulting from ternary system descriptions.

A Thermodynamic Approach to the Calculation of the C-Cr-Nb-Ni-W Phase Diagram

1982 ◽  
Vol 19 ◽  
Author(s):  
P.Y. Chevalier ◽  
J.N. Barbier ◽  
I. Ansara
Keyword(s):  
Phase Diagram ◽  
Thermodynamic Properties ◽  
Binary Systems ◽  
Thermodynamic Approach ◽  
Phase Boundaries ◽  
Quaternary Systems ◽  
Methods Of Calculation

ABSTRACTThe phase boundaries of the C-Cr-Nb-Ni-W system are calculated from the available thermodynamic properties of the limiting binary systems. The methods of calculation and the models used in the description of the ternary and quaternary systems are presented as well as the influence of tungsten on the solubility of the M23C6 phase in the nickel rich alloys.

Thermodynamic modeling of the Ni–Al–Ga–N system

2004 ◽  
Vol 19 (6) ◽  
pp. 1742-1751 ◽  
Author(s):  
B.A. Hull ◽  
S.E. Mohney ◽  
Z-K. Liu
Keyword(s):  
Thin Film ◽  
Binary Systems ◽  
Driving Forces ◽  
Recent Analysis ◽  
General Phenomenon ◽  
Phase Boundaries ◽  
Isothermal Sections ◽  
Component System ◽  
Quaternary Phase ◽  
Semiconductor Alloy

Isothermal sections in the Ni–Al–Ga–N quaternary phase diagram were calculated to provide a greater understanding of interfacial reactions between Ni contacts and AlxGa1−xN. The calculations were performed employing a thermodynamic database of the Ni–Al–Ga–N system that was constructed by combining the six binary systems of the four component system. The model of the Ga–N binary system was created in this work. The models of the Ni–Ga and Ni–Al systems, both of which were taken from the literature, were modified to be compatible with one another. Thermodynamic data and phase boundaries for other binary systems were taken from the literature, as was information on portions of the Al–Ga–N and Ni–Al–Ga phase diagrams. The calculated sections reveal that during reaction between Ni and AlxGa1−xN, Ni is favored to react with the GaN component of the semiconductor alloy, leaving an Al-enriched AlxGa1−xN. These predictions are consistent with a recent analysis of the Ni, Al, and Ga elemental distributions across the interface between a Ni thin film and an Al0.47Ga0.53N epitaxial layer following annealing at 850 °C. Consideration of the thermodynamic driving forces suggests that this may be a general phenomenon existing in other metal–Al–Ga–N systems.

Effect of grain and phase boundaries on soft magnetic properties of FeCoNiAlSi high-entropy alloys

2021 ◽  
pp. 129965
Author(s):  
Zhong Li ◽  
Jianing Qi ◽  
Zhuangzhuang Li ◽  
Hongxia Li ◽  
Hui Xu ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
High Entropy Alloys ◽  
Soft Magnetic Properties ◽  
Soft Magnetic ◽  
Phase Boundaries ◽  
High Entropy

Calculation of phase diagrams and thermodynamic properties of 14 additive and reciprocal ternary systems containing Li2CO3, Na2CO3, K2CO3, Li2SO4, Na2SO4, K2SO4, LiOH, NaOH, and KOH

1984 ◽  
Vol 62 (3) ◽  
pp. 457-474 ◽  
Author(s):  
A. D. Pelton ◽  
C. W. Bale ◽  
P. L. Lin
Keyword(s):  
Phase Diagram ◽  
Thermodynamic Properties ◽  
Molten Salt ◽  
Phase Diagrams ◽  
Binary Systems ◽  
Ternary Phase ◽  
Ternary Phase Diagram ◽  
Ternary Systems ◽  
Maximum Error ◽  
Critical Assessment

Phase diagrams and thermodynamic properties of five additive molten salt ternary systems and nine reciprocal molten salt ternary systems containing the ions Li+, Na+, [Formula: see text], OH− are calculated from the thermodynamic properties of their binary subsystems which were obtained previously by a critical assessment of the thermodynamic data and the phase diagrams in these binary systems. Thermodynamic properties of ternary liquid phases are estimated from the binary properties by means of the Conformal Ionic Solution Theory. The ternary phase diagrams are then calculated from these thermodynamic properties by means of computer programs designed for the purpose. It is found that a ternary phase diagram can generally be calculated in this way with a maximum error about twice that of the maximum error in the binary phase diagrams upon which the calculations are based. If, in addition, some reliable ternary phase diagram measurements are available, these can be used to obtain small ternary correction terms. In this way, ternary phase diagram measurements can be smoothed and the isotherms drawn in a thermodynamically correct way. The thermodynamic approach permits experimental data to be critically assessed in the light of thermodynamic principles and accepted solution models. A critical assessment of error limits on all the calculated ternary diagrams is made, and suggestions as to which composition regions merit further experimental study are given.

scholarly journals A Review on the High Temperature Strengthening Mechanisms of High Entropy Superalloys (HESA)

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5835
Author(s):  
Malefane Joele ◽  
Wallace Rwisayi Matizamhuka
Keyword(s):  
High Temperature ◽  
Configurational Entropy ◽  
Extended Period ◽  
Theoretical Models ◽  
Intermetallic Phases ◽  
Processing Route ◽  
Strengthening Mechanisms ◽  
High Entropy ◽  
Use Of Resources ◽  
The Impact

The studies following HEA inceptions were apparently motivated to search for single-phase solid solution over intermetallic phases, accordingly made possible by the concept of high configurational entropy. However, it was realised that the formation of intermetallic phases in HEAs is prevalent due to other criterions that determine stable phases. Nonetheless, recent efforts have been directed towards attributes of microstructural combinations. In this viewpoint, the techniques used to predict microstructural features and methods of microstructural characterisation are elucidated in HESA fields. The study further analyses shortcomings regarding the design approaches of HESAs. A brief history is given into how HESAs were developed since their birth, to emphasize the evaluation techniques used to elucidate high temperature properties of HESAs, and the incentive thereof that enabled further pursuit of HESAs in the direction of optimal microstructure and composition. The theoretical models of strengthening mechanisms in HEAs are explained. The impact of processing route on the HESAs performance is analysed from previous studies. Thereafter, the future of HESAs in the market is conveyed from scientific opinion. Previous designs of HEAs/HESAs were more based on evaluation experiments, which lead to an extended period of research and considerable use of resources; currently, more effort is directed towards computational and theoretical methods to accelerate the exploration of huge HEA composition space.

Thermodynamic Calculation of Phase Equilibria in the Mn-RE (RE=Nd, Gd, Dy) Binary Systems

2017 ◽  
Vol 898 ◽  
pp. 1036-1041
Author(s):  
M.H. Rong ◽  
S.D. Lin ◽  
Jiang Wang ◽  
H.Y. Zhou ◽  
G.H. Rao
Keyword(s):  
Magnetic Properties ◽  
Thermodynamic Properties ◽  
Phase Equilibria ◽  
Thermodynamic Calculation ◽  
Binary Systems ◽  
Ternary Systems ◽  
Experimental Information ◽  
Calphad Method ◽  
Self Consistent ◽  
Ternary Intermetallic Compounds

Ternary intermetallic compounds with rare earth elements and transition metals in the RE-Mn-X (X=Si, Ge, Sn etc.) ternary systems show interesting magnetic properties. As key sub-binary systems of the RE-Mn-X (X=Si, Ge, Sn etc.) ternary systems, the information of phase equilibria and thermodynamic properties of the Mn-RE (RE=Nd, Gd, Dy) binary systems are indispensable to explore the RE-Mn-X (X=Si, Ge, Sn etc.) alloys with better magnetic properties. In this work, the experimental data of phase equilibria and thermodynamic properties of the Mn-RE (RE=Nd, Gd, Dy) binary systems in the published literature were reviewed. Based on the available experimental information, thermodynamic calculation of phase equilibria of the Mn-RE (RE=Nd, Gd, Dy) binary systems was performed using the CALPHAD method. As a result, further experimental investigation and thermodynamic optimization would be still necessary in order to develop the self-consistent and compatible thermodynamic database of the RE-Mn-based alloy systems.

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