Subregular Solution Model Research Articles

Activity Calculation and Vacuum Separation Theoretical Research concerning Ag–Cu, Ag–Sb and Cu–Sb Binary Alloys

The Ag–Cu–Sb system is a key component of lead anode slime and boasts an exceptionally high economic recovery value. In this work, six models, including the Molecular Interaction Volume Model (MIVM), Modified Molecular Interaction Volume Model (M-MIVM), Wilson equation, Miedema model, Regular Solution Model (RSE) and Sub-Regular Solution Model (SRSE), are used to calculate the predicted values of the activity and its deviations with experimental data for binary alloys in the Ag–Cu–Sb system for the first time. The result reveals that the overall means of the average relative deviation and average standard deviation of the M-MIVM are 0.01501 and 3.97278%, respectively, which are about two to six times smaller than those of the other five models, indicating the stability and reliability of the M-MIVM. In the meantime, the predicted data of the Cu–Ag binary alloy at 1423 K, Sb–Ag binary alloy at 1250 K and Sb–Cu binary alloy at 1375 K calculated from the M-MIVM are more reliable and pass the Herington test. Then, the separation coefficient–composition (β–x), temperature–composition (T–x–y) and pressure–composition (P–x–y) of the Cu–Ag, Sb–Ag and Sb–Cu binary alloys are plotted based on the M-MIVM and vacuum theories, showing that the Cu–Ag binary alloy is relatively difficult to separate and that high temperatures or high copper contents are detrimental to obtaining high-purity silver. Meanwhile, theoretical data of the T–x–y diagram are consistent with the available experimental data. These results can guide vacuum separation experiments and industrial production concerning Ag–Cu, Ag–Sb and Cu–Sb binary alloys.

Experimental determination and thermodynamic optimization of the LiF-NdF3 system.

Neodymium is mainly obtained by electrolysis of a molten LiF-NdF3-Nd2O3 system. LiF-NdF3 is a basic system, and the phase diagram of this system provides important information in the production of electrolytic neodymium. An accurate LiF-NdF3 binary phase diagram helps in the selection of the appropriate molten salt component in production and optimizing the production process, which is of great significance to improve the electrolysis efficiency and reduce the production cost. To obtain an accurate phase diagram of the LiF-NdF3 binary system, liquidus and solidus temperatures were experimentally determined in the LiF-NdF3 binary system by differential scanning calorimetry. The experimental results were used to construct the phase diagram and develop a new database for the LiF-NdF3 system using the FactSage software. The sub-regular solution model was used to describe the excess Gibbs free energy of the liquid phase, and the thermodynamic optimization calculation was carried out for the binary system. The binary interaction coefficients 0L = -39 966 + 17.68 T, 1L = -7667 + 26.1 T, and 2L = -6000 were used to describe the system's excess Gibbs free energy. The results show that the eutectic point of the system is 68.4% LiF-31.6% NdF3 at 731.5 °C. The effects of industrial and high purity NdF3 and the presence of Nd2O3 on the liquidus temperature of the LiF-NdF3 system were also investigated, high liquidus temperatures have been observed in tests using industrial NdF3 and NdF3 feedstock that contains a specific quantity of Nd2O3.

Aluminum Deoxidation Equilibrium in Molten Fe-Co Alloys

Aluminum deoxidation equilibrium of molten Fe-Co alloy was experimentally measured using a chemical equilibrium method and numerically assessed using a sub-regular solution model based on Darken’s quadratic formalism and a Redlich-Kister type polynomial at 1873 K. It was found that the degree of oxygen content reduction by Al-deoxidation decreased with increasing cobalt concentration in the alloy, peaking at around 40 to 60 mass% Co, and then improved with further increase in cobalt concentration. The following binary interaction parameters between cobalt and aluminum were derived in this study:

Atom Probe Study of the Miscibility Gap in CuNi Thin Films and Microstructure Development.

The unclear miscibility of CuNi alloys was investigated with atom probe tomography (APT). Multilayered thin film samples were prepared by ion beam sputtering (IBS) and focused ion beam (FIB) shaping. Long-term isothermal annealing treatments in a UHV furnace were conducted at temperatures of 573, 623, and 673 K to investigate the mixing process. The effective interdiffusion coefficient of the nanocrystalline microstructure (including defect diffusion) was determined to be Deff = 1.86 × 10−10 m2/s × exp(−164 kJ/mol/RT) by fitting periodic composition profiles through a Fourier series. In nonequilibrium states, microstructural defects like grain boundaries and precipitates were observed. While at the two higher temperatures total mixing is observed, a clear experimental evidence is found for a miscibility gap at 573 K with the boundary concentrations of 26 and 66 at%. These two compositions are used in a subregular solution model to reconstruct the phase miscibility gap. So, the critical temperature TC of the miscibility gap is found to be 608 K at a concentration of 45 at% Ni.

Phase-Field Simulation of Spinodal Decomposition in Mn-Cu Alloys

The spinodal decomposition was studied in the aged Mn-40 at. %Cu, Mn-30 at. %Cu, Mn-20 at. %Cu alloys using a phase-field model based on the Cahn–Hillard equation, considering a subregular solution model and the energy contribution of the magnetic behavior. The simulations were performed at aging temperatures of 300, 400, and 500 °C for times from 1 to 240 min. The growth kinetics of the Mn concentration profiles with time indicated clearly that the phase decomposition of the supersaturated solid solution γ into a mixture of Mn-rich γ′ and Cu-rich γ phases occurred by the spinodal decomposition mechanism. Moreover, the phase decomposition at the early stages of aging exhibited the characteristic morphology of spinodal decomposition, an interconnected and percolated microstructure of the decomposed phases. The most rapid growth kinetics of spinodal decomposition occurred for the aging of Mn-20 and 30 at. %Cu alloys because of the higher driving force. The presence of the phase decomposition is responsible for the increase in hardness, as well as the improvement of the damping capacity of Mn-Cu alloys.

First-principles calculations and thermodynamic assessment of the Nb–V system using CE-CVM

A thermodynamic assessment of the Nb–V system has been carried out based on first-principles calculations and all the available experimental thermodynamic and phase equilibria data. Mixed-parametric ab initio calculations were performed to calculate the enthalpy of mixing data with Special quasirandom structures (SQS) and cluster expansion (CE) method. The Gibbs energy of the bcc solid phase was described using tetrahedron approximation of the Cluster Expansion and Cluster Variation Methods (CE-CVM). A sub-regular solution model was used for describing Gibbs energy of the liquid phase. An optimal set of parameters has been obtained for describing the Gibbs energies of the liquid and solid phases in the Nb–V binary system. The calculated phase diagram and thermodynamic properties agree with experimental data. The relevance of CE-CVM has been demonstrated in the present case by calculating the solid phase's short-range order (sro) parameters as a function of composition and temperature.

Equilibrium phase diagrams of isostructural and heterostructural two-dimensional alloys from first principles

SummaryAlloying is a successful strategy for tuning the phases and properties of two-dimensional (2D) transition metal dichalcogenides (TMDCs). To accelerate the synthesis of TMDC alloys, we present a method for generating temperature-composition equilibrium phase diagrams by combining first-principles total-energy calculations with thermodynamic solution models. This method is applied to three representative 2D TMDC alloys: an isostructural alloy, MoS2(1-x)Te2x, and two heterostructural alloys, Mo1-xWxTe2 and WS2(1-x)Te2x. Using density-functional theory and special quasi-random structures, we show that the mixing enthalpy of these binary alloys can be reliably represented using a sub-regular solution model fitted to the total energies of relatively few compositions. The cubic sub-regular solution model captures 3-body effects that are important in TMDC alloys. By comparing phase diagrams generated with this method to those calculated with previous methods, we demonstrate that this method can be used to rapidly design phase diagrams of TMDC alloys and related 2D materials.

Thermodynamic assessment of the miscibility gaps and the metastable liquidi in the Zn‐Bi, Zn‐Pb, and Zn‐Tl systems

Abstract In monotectic systems, there are thermodynamic restrictions on compositions and temperatures below the monotectic where the equilibrium solid cannot form directly from the undercooled homogeneous liquid. In this region, the solid can form only after liquid – liquid phase separation has occurred. As suggested by earlier research, the thermodynamic restrictions on the solidification process may be useful to control the microstructure of rapidly solidified materials. Thus, it could be commercially important to understand the thermodynamic limitations on the formation of the solid in monotectic systems. The liquid miscibility gaps, metastable liquidi, and spinodal curves in the binary Zn– Bi, Zn–Pb, and Zn–Tl systems were assessed by using a subregular solution model to describe the Gibbs energies of the liquid phases. The present results were compared and discussed with other experimental and assessed data available in the literature.

Thermal stability, hydrolysis and thermodynamic properties of molten KCl-CuCl

KCl-CuCl is known as an inorganic salt mixture with a particularly low melting point, below 200 °C. There are very few studies published investigating this binary system. In this study KCl-CuCl is considered as a candidate for liquifying biomass as a pre-step before a high pressure and temperature (40–50 bar, 450–500 °C) hydro-pyrolysis process. Its low melting point makes it a good candidate to liquify biomass at mild conditions (low temperature and pressure) and avoid producing char and ash. Thermal stability and stability against hydrolysis have been measured for compositions close to the eutectic composition up to 500 °C. The results show that KCl-CuCl is thermally stable, and no mass loss was observed up to 500 °C. Moreover, it is chemically stable in contact with water and no HCl was detected in hydrolysis experiments. In addition, the modelling of the system was studied. Although there is a phase diagram for this system in the literature based on the experimental data, no thermodynamic parameters have been calculated for this system and no database was found for KCl-CuCl solution. Therefore, Calphad modelling of the binary KCl-CuCl molten salt is performed in this study and FactSage is employed to assess the thermodynamic parameters and generate the phase diagram. For this purpose, a series of experiments have been carried out to investigate transition points and thermodynamic properties of mixtures between 40 and 80 mol% of CuCl by cooling curve and differential scanning calorimetry. The intermediate compound K 2 CuCl 3 is considered stoichiometric, and its Gibbs energy modelling relies on ab initio calculated enthalpy of reaction from the base salts and optimization of the standard entropy. The liquid solution is modelled with a subregular solution model using Redlich-Kister polynomials. The phase diagram of the system is generated based on thermodynamic data and experimental results. The results show that the predicted eutectic point of the binary system is located at T = 145.9 °C and 64.9 CuCl mol%. The calculated results are in excellent agreement with the measured values. The high thermal stability and stability against hydrolysis qualify eutectic KCl-CuCl mixtures as promising molten salt for biomass liquefaction. However, corrosion limits the choice of possible reactor materials.

Notes on the creation and manipulation of solid solution models

A large class of solid solution models are formulated on the premise that exchange of chemical species takes place on a finite number of unique crystallographic sites, and that the thermodynamic properties of the solution are a function of the proportions of species occupying each of the sites. These models are broadly classified as being of Bragg–Williams-type. They form an excellent first order approximation of non-ideal mixing and long-range order. In this article we present the mathematical framework common to all Bragg–Williams models, introducing necessary concepts from geometry, set theory and linear algebra. We combine this with a set of mathematical tools which we have found useful in building and using such models. We include several worked examples to illustrate key concepts and provide general expressions which can be used for all models. This paper is split into two parts. In the first part, we show how the valences of the species occupying each site and the total charge of the species involved in site exchange are sufficient to define the space of valid site occupancies of a solid solution, and to compute the endmembers bounding that space. We show that this space can be visualised as a polytope, i.e, an n-dimensional polyhedron, and we describe the relationship between site-occupancy space and compositional space. In the second part of the paper, we present the linear algebra required to transform descriptions of modified van Laar and subregular solution models from one independent endmember basis to another. The same algebra can also be used to derive macroscopic endmember interactions from microscopic site interactions. This algebra is useful both in the initial design of solution models, and when performing thermodynamic calculations in restricted chemical subsystems. A polytope description of solid solutions is used in the thermodynamic software packages Perple_X and burnman. The algorithms described in this paper are made available as python code.

Thermodynamics and vaporization of the Sm2O3–ZrO2 system studied by Knudsen effusion mass spectrometry

The purpose of the present study was to examine the thermodynamic properties and vaporization processes in the Sm2O3–ZrO2 system by the Knudsen effusion mass spectrometric method (KEMS). The samples in the system under consideration were synthesized by the solid-state method using a high-energy ball mill. Vapor over the Sm2O3–ZrO2 system consisted of SmO, Sm, and O in the temperature range 2200–2540 K. Concentration dependences of the SmO and Sm partial vapor pressures, the component activities, and excess Gibbs energies were obtained at a temperature of 2452 K in the compositional range of 0.23–0.73 Sm2O3 mole fraction. These data evidenced negative deviations from the ideal behavior and a possibility to use the subregular solution model to describe the concentration dependences of the thermodynamic properties in the Sm2O3–ZrO2 system. Correlations were found between the observed changes in the thermodynamic behavior of the system mentioned and the relative number of bonds when the second coordination sphere was taken into consideration in the condensed phase calculated by the Generalized Lattice Theory of Associated Solutions.

Measurement and Thermodynamics of Carbon Solubilities in Molten Si–Fe, Si–Ni, and Si–Cr–Fe Alloys at 2073 K

The equilibrium phase relations of molten Si–Fe, Si–Ni, and Si–Fe–Cr alloys saturated with either silicon carbide (SiC) or graphite, which are candidates for the solvent for rapid solution growth of SiC, have been investigated. The measured carbon solubilities at 2073 K were 0.19–6.6 mol% for the Si–(24.1–70.1) mol% Fe, 0.061–5.2 mol% for Si–(30.0–85.0) mol% Ni, and 1.1–3.9 mol% for Si–(50−x) mol% Fe–x mol% Cr (x = 10.4–40.1) alloys. A quasi-chemical model that assumes that the carbon atoms are introduced into the interstitial sites of the Si–Fe, Si–Ni, and Si–Fe–Cr solvents and obstruct the bonding between solvent atoms was used to evaluate the activity coefficient of carbon in each alloy. The estimation reproduced the trends of the measured carbon solubilities fairly well. However, the estimation using the sub-regular solution model often overestimated the carbon solubilities. Thus, the carbon behavior in molten silicon–transition metal alloys is well described by the quasi-chemical model.

The lattice parameter – composition relationship of the body centered cubic uranium-niobium alloys

In-situ time-of-flight neutron diffraction experiments were performed on uranium-niobium alloy with 6 wt% Nb to study the lattice parameter-composition relationship for the body centered cubic (bcc) alloys. Based on lattice-parameter measurements of Nb-supersaturated γs phase over the range of 450 – 790 °C, an improved Vegard's-type relationship was established for determination of Nb concentrations at elevated temperatures. Neutron diffraction data were also collected as a function of aging time over the 450 - 600 °C range when γs phase decomposed isothermally into the mixture of orthorhombic α-U and Nb-rich bcc phase, as well as at room-temperature on the alloys aged ex-situ at 500 °C up to five years. From these measurements, the average Nb concentrations in the bcc phase were determined based on the Rietveld refinements of weight fraction and mass conservation relations (lever rule). Over the 15at% – 78at% range of Nb concentrations that correspond to different experimental aging times, the lattice parameters at constant temperatures exhibit a nonlinear S-shaped variation with Nb concentration, and the associated excess volumes of mixing can be described by a subregular solution model of the Redlich–Kister type of polynomial. Over the full range of composition the S-shaped deviation from Vegard's law can be modeled using a combination of an elastic continuum model and a perturbation to the radii of the solute atoms in the solvent, suggesting that electronic interactions between solute and solvent atoms could play an important role in the compositional dependence of lattice parameter for the γ-phase U-Nb alloys. While Vegard's law is a straightforward and reasonably good approximation for the bcc solid solutions in the U-Nb system, the Nb concentrations determined from the weight fraction refinements of diffraction data provide internally consistent, mass-conserving estimates of solute redistribution for the monotectoid reaction.

Mixing Entropy of Exact Equiatomic High-Entropy Alloys Formed into a Single Phase

Exact equiatomic high-entropy alloys (EE-HEAs) comprising N elements (N ≥ 5) formed into a single phase with either bcc, fcc or hcp structure were investigated based on sub-regular solution model. The analysis was performed by utilizing relationships among Gibbs energy (G), enthalpy (H), entropy (S), absolute temperature (T) and pressure (P), G = H − TS and S = −(∂G/∂T)P, for representative EE-HEAs, such as bcc-MoNbTaVW, fcc-CoCrFeMnNi and hcp-EE-HEAs comprising heavy lanthanides with and without Y. Mixing entropy (Smix) was evaluated as the sum of excess entropy (Sexcess) and ideal entropy (Sideal), the latter of which is equivalent to configuration entropy (Sconfig). Calculation tools contained commercial software (Thermo-Calc 2020a) using a database for HEAs (TCHEA4) mainly for the bcc- and fcc-EE-HEAs and that for solid solutions (SSOL5) for the hcp-EE-HEAs. The analysis revealed that the bcc-MoNbTaVW and NbTaTiVW HEAs exhibited the greatest decrease in Smix normalized with gas constant (R) down to approximately 87% of Sideal/R = ln N due to a positive T dependence of interaction parameter, Ωi−j(T), of i-j atomic pairs in mixing enthalpy (Hmix). In contrast, Smix/R of the fcc-CoCrFeMnNi HEA was approximately 9% greater than ln N. The hcp-EE-HEAs from a class of athermal solutions behaved as ideal solutions in practice. The results revealed that a relationship of Smix/R = ln N does not always hold in EE-HEAs.

Experimental investigation of phase relations in the system NaAlSi3O8–H2O at high temperatures and pressures: liquidus relations, liquid–vapor mixing, and critical phenomena at deep crust–upper mantle conditions

Supercritical fluids in rock–H2O systems have been proposed to be important agents of mass transfer in subduction zone environments. New experimental studies were conducted on the simple model granite system NaAlSi3O8 (Ab)–H2O in order to investigate phase relations and to develop the thermodynamic mixing properties between aqueous fluid (a.k.a. vapor, V) and silicate melt (a.k.a. liquid, L) at pressures (P) and temperatures (T) approaching those of critical mixing. We established liquidus and solvus phase relations by analyzing the quenched run products from piston–cylinder experiments over a range of $$P - T - X_{{{\text{H}}_{2} {\text{O}}}}$$ conditions from 1.0 to 1.7 GPa, 630–1060 °C and 4–92 wt% H2O. Equations for the critical curve, solidus temperatures, albite solubility at the solidus, and vapor-saturated solidus H2O content were formulated as functions of $$P - T - X_{{{\text{H}}_{2} {\text{O}}}}$$ . We constructed a subregular solution model to describe the solvus curves using P and T dependent Margules coefficients ( $$W_{{{\text{H}}_{2} {\text{O}}}}$$ and $$W_{\text{Ab}}$$ ). Activities of H2O and Ab ( $$a_{{{\text{H}}_{2} {\text{O}}}}$$ and $$a_{\text{Ab}}$$ ) could be formulated using only the input at the solidus and the critical point at each pressure because of the nearly linear dependence of the parameters on T. The solvus curves were confirmed independently by means of criteria established for classification of quenched products as L, L + V, or V and are in excellent agreement with the compositions that can be calculated using the Margules coefficients. At 1.6 GPa, the H2O content at the vapor-saturated solidus is 44.5 ± 5.5 wt% and the solubility of albite at the solidus is 42.95 ± 0.99 wt%, indicating the imminent intersection of the two curves and thus a stable critical endpoint at some slightly higher pressure. We constrain the critical endpoint at 1.63 ± 0.02 GPa, 659 ± 5 °C, and a composition of ~ 44.7 wt% H2O based on the intersections of the pressure dependent solidus curves with the critical curve, the pressure dependent albite solubility curve with the vapor-saturated solidus curve. The 1.7 GPa experiments showed no evidence for liquid–vapor immiscibility across a wide range of compositions and temperatures (4–80 wt% H2O and 630–1050 °C, and furthermore, that low albite is stable in the presence of the supercritical fluid near the breakdown of albite to jadeite and quartz. These results provide a comprehensive account of the solution properties of subcritical and supercritical fluids in this model granite system at temperatures and pressures corresponding to the deep-crust regions of granite magma generation.

Composition and processing design of medium-Mn steels based on CALPHAD, SFE modeling, and genetic optimization

Medium-Mn steels are being thoroughly investigated as potential candidates for the 3rd generation of advanced high strength steels. Despite the wide experimental work, limited attempts have been presented to systematically optimize the chemical composition and heat treatment process to obtain desired microstructural features. In the present work, CALPHAD-based thermodynamic and kinetic modeling, coupled with multi-objective genetic optimization was adopted for the development of δ-ferrite containing medium-Mn steels with optimized microstructure, meeting set design requirements associated with retained austenite fraction and stability. A new sub-regular solution model for the prediction of the austenite stacking fault energy (SFE) was developed and compared to experimental literature data. A MATLAB implementation of the SFE model is provided as supplementary material. Pareto optimal compositions and associated process windows were identified via thermodynamic modeling coupled with the NSGA-II algorithm. A single optimized steel was selected for further consideration through kinetic simulation of the entire process chain including solidification, hot-rolling, accelerated cooling, quenching, and intercritical annealing, considering the effect of δ-ferrite on retained austenite stability and the martensite to austenite transformation kinetics. Temporal optimization resulted in the selection of an optimal intercritical annealing time. Model predictions were validated with metallographic observations on two different δ-ferrite containing medium-Mn steels, revealing excellent agreement between predicted and observed phase fractions.

Non-stoichiometry Effects and Phase Equilibria in the Uranium-Carbon-Nitrogen Ternary System

Uranium carbonitride—a solid solution of stoichiometric UC and UN compounds—is considered as a potential nuclear fuel, and is only one of multiple phases that occur in the ternary U-C-N system. Explanation of available observed data and successful synthesis of the ternary U(C, N) compound requires understanding of complex phase equilibria that take place in the system. A subregular solution model is introduced to account for the non-stoichiometry of two-component solid phases (α-, β-UC2, α-U2N3), and an ideal solution model—for the substitutional nature of C–N interactions in the non-metal sublattice of U(C, N). The model better reproduces the phase fields compared to the previously reported approach, and is in good agreement with the available observed data. The stability diagram of U(C, N) with its composition and temperature (or pressure) as axes is used to compare the model predictions and the observed equilibrium data. While the theory is consistent with the available data, there is a certain disagreement with the observed equilibrium N2 partial pressure.

Anomalous pressure dependent phase diagram of liquid Ga–In alloys

Pressure dependent phase diagram of liquid Ga–In alloys was calculated using high accuracy measurements of sound velocity and density at ambient conditions. In particular, the eutectic temperature and composition were found to have anomalous dependence on pressure. These alloys belong to a new class of room-temperature liquid metals, which are considered for multiple novel applications. To establish a pressure dependent phase diagram, we have measured to high accuracy sound velocity and density measurements across a wide range of temperatures and compositions. The sound velocity and density of the Ga–In system in the liquid phase were measured by a modified pulse-echo technique and the constrained drop method respectively. Implementing a sub-regular solution model, the pressure dependence of the Ga–In phase diagram was calculated. The new phase diagram was corroborated by a novel experimental measurement of the eutectic temperature as a function of pressure, utilizing a Paris-Edinburgh high-pressure large volume cell. The eutectic composition and temperature are found to depend strongly on pressure, information which extends our understanding of the Ga–In system and its possible applications.

Thermodynamics of the Ca(NO3)2 – NaNO3 system

Thermodynamic properties of the quasi binary Ca(NO3)2–NaNO3 system are of interest with respect to thermal energy storage. In the present work the phase diagram as well as thermodynamic properties of the near eutectic mixture 45 mol% Ca(NO3)2 – 55 mol% (NaNO3)2 were determined experimentally and applied in the assessment of a new Gibbs energy dataset for thermochemical calculations. The enthalpy of fusion of the 45 mol% Ca(NO3)2 – 55 mol% (NaNO3)2 mixture is determined to be 24.7 ± 0.5 kJ/mol. The melting and crystallization enthalpy have good reproducibility, which makes it possible to use this mixture as a phase change material at temperature 225 °C. The assessed dataset describes liquid phase properties using a subregular solution model in the Redlich-Kister formalism with high accuracy. Therefore it can be used for the prediction of thermodynamic properties of different compositions in the whole Ca(NO3)2–NaNO3 system and be included in databases for calculation of multicomponent systems including other components.

The equilibrium phase diagram of the pentaerythritol-pentaglycerine-2-amino-2methyl-1,3, propanediol (PE-PG-AMPL) system

Polyalcohols and amines have been considered as potential thermal energy storage materials, owing to their energetic solid-solid phase transitions. In this paper, we present equilibrium phase diagram of Pentaerythritol (PE)–Pentaglycerine (PG)– 2-amino-2methyl-1,3, propanediol (AMPL) ternary system that has been thermodynamically assessed using the CALPHAD method. A special class of, so called, “Plastic Crystals” have tetrahederally configured molecules with O–H⋯O or N–H⋯O layered or chained bonds in the low temperature phase, and store latent heat of transformation during solid-solid phase change in orientationally disordered crystals at higher temperatures. For example, in polyalcohols, there are O–H⋯O bond rotations around the C–C bonds that are responsible for storing large amounts of solid state phase change energy. Several binary equilibrium phase diagrams of polyalcohols, amines and combination thereof have been calculated and experimentally validated. We only know of three ternary phase diagram of these plastic crystals reported, to the best of knowledge. In the thermodynamic calculations of thePE-PG-AMPL system, we used the binary phase diagram experimental data for the optimization and calculation of excess energies. The binary systems have been optimized using regular and sub-regular solution models. The binaries as well as the ternary system have been calculated from room temperature to the liquid phase. The solution phases are modeled as substitutional solutions, in which the excess Gibbs energies are expressed by the Redlich–Kister–Muggianu polynomial. There is a very good agreement between previously reported experimental data and the calculated phase diagrams.