Pub Date : 2024-11-04DOI: 10.1016/j.calphad.2024.102761
Melting temperature (Tm) is a crucial physical property of solids and plays an important role in the characterization of materials. Therefore, the capacity to predict Tm is a relevant issue for solid state sciences. This investigation aims i) to provide a theoretical basis for the link between catastrophe theory and thermodynamic instability; ii) to estimate Tm through the notion of “degenerate critical temperature” (Td), related to (Pd,Vd,Td), where KT → 0 and the Gibbs function shows a non-Morse behaviour; iii) to compare predictions of (Pm,Tm) with observations for three crystalline pure substances that undergo congruent melting and exhibit different bonding and stability ranges: NaCl (halite), SiO2,st (stishovite), and MgSiO3 (perovskite). The P-T locus of KT = 0 associated with melting is identified using the maximum values of Td and ΔH/ΔV at a given pressure. We observed an average absolute discrepancy ranging between 0.2 % (halite) and 5.8 % (stishovite), and an agreement between theoretical and experimental T(P)melting-points from better than 1 to approximately 14 %.
{"title":"Catastrophe theory and thermodynamic instability to predict congruent melting temperature of crystals","authors":"","doi":"10.1016/j.calphad.2024.102761","DOIUrl":"10.1016/j.calphad.2024.102761","url":null,"abstract":"<div><div>Melting temperature (<em>T</em><sub>m</sub>) is a crucial physical property of solids and plays an important role in the characterization of materials. Therefore, the capacity to predict <em>T</em><sub>m</sub> is a relevant issue for solid state sciences. This investigation aims i) to provide a theoretical basis for the link between catastrophe theory and thermodynamic instability; ii) to estimate <em>T</em><sub>m</sub> through the notion of “degenerate critical temperature” (<em>T</em><sub>d</sub>), related to (<em>P</em><sub>d</sub>,<em>V</em><sub>d</sub>,<em>T</em><sub>d</sub>), where <em>K</em><sub><em>T</em></sub> → 0 and the Gibbs function shows a <em>non</em>-Morse behaviour; iii) to compare predictions of (<em>P</em><sub>m</sub>,<em>T</em><sub>m</sub>) with observations for three crystalline pure substances that undergo congruent melting and exhibit different bonding and stability ranges: NaCl (halite), SiO<sub>2,st</sub> (stishovite), and MgSiO<sub>3</sub> (perovskite). The <em>P</em>-<em>T locus</em> of <em>K</em><sub><em>T</em></sub> = 0 associated with melting is identified using the maximum values of <em>T</em><sub>d</sub> and Δ<em>H</em>/Δ<em>V</em> at a given pressure. We observed an average absolute discrepancy ranging between 0.2 % (halite) and 5.8 % (stishovite), and an agreement between theoretical and experimental <em>T</em>(<em>P</em>)<sub>melting</sub>-points from better than 1 to approximately 14 %.</div></div>","PeriodicalId":9436,"journal":{"name":"Calphad-computer Coupling of Phase Diagrams and Thermochemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142577460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.calphad.2024.102764
Quantitative modelling of precipitation kinetics can play an important role in a computational materials design framework. For many material systems, e.g., the Fe-Cu system, the precipitates (rich in Cu at equilibrium) nucleate at a composition far away from the equilibrium. This in turn affects the precipitation kinetics, and the capability to model the compositional evolution of the Cu precipitates is therefore important. In the present work we propose a new approach implemented in a Langer-Schwartz-Kampmann-Wagner precipitation modelling framework where the concentration profile inside the precipitates is defined with an explicit function and the diffusive fluxes in both precipitates and matrix are solved concurrently to compute the growth rate of the precipitates. The new model is evaluated with respect to results from atom probe tomography for Cu precipitation in a 15–5 PH stainless steel. A parameter study of the effect of diffusion coefficients and interfacial energies is conducted, and it is concluded that the new model is capable of describing the experimentally determined evolution of the Cu precipitate volume fraction, mean radius, number density and composition.
{"title":"A new model for precipitation kinetics considering diffusion within the precipitates","authors":"","doi":"10.1016/j.calphad.2024.102764","DOIUrl":"10.1016/j.calphad.2024.102764","url":null,"abstract":"<div><div>Quantitative modelling of precipitation kinetics can play an important role in a computational materials design framework. For many material systems, e.g., the Fe-Cu system, the precipitates (rich in Cu at equilibrium) nucleate at a composition far away from the equilibrium. This in turn affects the precipitation kinetics, and the capability to model the compositional evolution of the Cu precipitates is therefore important. In the present work we propose a new approach implemented in a Langer-Schwartz-Kampmann-Wagner precipitation modelling framework where the concentration profile inside the precipitates is defined with an explicit function and the diffusive fluxes in both precipitates and matrix are solved concurrently to compute the growth rate of the precipitates. The new model is evaluated with respect to results from atom probe tomography for Cu precipitation in a 15–5 PH stainless steel. A parameter study of the effect of diffusion coefficients and interfacial energies is conducted, and it is concluded that the new model is capable of describing the experimentally determined evolution of the Cu precipitate volume fraction, mean radius, number density and composition.</div></div>","PeriodicalId":9436,"journal":{"name":"Calphad-computer Coupling of Phase Diagrams and Thermochemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.calphad.2024.102758
The P-Si system has been studied due to its poisonous importance in silicon electronic devices for photovoltaic applications. Thermodynamic and phase diagram data of the Si-P system available in literature are critically evaluated for further optimization of thermodynamic properties in order to improve the thermodynamic description of this system, especially in the Si-rich region. After revising the solubility data of P in solid Si in the Si-rich region its upper limit is now evaluated at 1w% P (mole fraction XP ≈ 0.0095). With this controversial solubility limit resolved, current modelling of the liquid and solid phases is described more accurately. Distillation capacity of phosphorus by vaporization is then assessed for liquid and solid silicon on the basis of the determination of the infinite dilution activity coefficient of phosphorus in silicon - the Henry's coefficient - as well as numerous gaseous species existing in the Si-P binary system. The lack of original calorimetric data is highlighted in view to a further more reliable description of the complete Si-P system.
由于 P-Si 系统在光伏应用的硅电子设备中具有重要的毒害作用，因此对该系统进行了研究。为了进一步优化热力学特性，我们对文献中提供的硅-硅体系的热力学和相图数据进行了严格评估，以改进该体系的热力学描述，尤其是在富硅区域。在修订了固态硅中 P 在富硅区域的溶解度数据后，其上限现在被评估为 1w% P（分子分数 XP ≈ 0.0095）。解决了这一有争议的溶解度上限问题后，目前对液相和固相的建模描述就更加准确了。然后，在确定硅中磷的无限稀释活性系数（亨利系数）以及硅-磷二元体系中存在的众多气态物质的基础上，对液态和固态硅的磷蒸发蒸馏能力进行了评估。为了进一步更可靠地描述完整的硅-磷系统，强调了原始量热数据的缺乏。
{"title":"Critical assessment of the Si-P system: P solubility in the Si-rich region and refining by phosphorus distillation","authors":"","doi":"10.1016/j.calphad.2024.102758","DOIUrl":"10.1016/j.calphad.2024.102758","url":null,"abstract":"<div><div>The P-Si system has been studied due to its poisonous importance in silicon electronic devices for photovoltaic applications. Thermodynamic and phase diagram data of the Si-P system available in literature are critically evaluated for further optimization of thermodynamic properties in order to improve the thermodynamic description of this system, especially in the Si-rich region. After revising the solubility data of P in solid Si in the Si-rich region its upper limit is now evaluated at 1w% P (mole fraction X<sub>P</sub> ≈ 0.0095). With this controversial solubility limit resolved, current modelling of the liquid and solid phases is described more accurately. Distillation capacity of phosphorus by vaporization is then assessed for liquid and solid silicon on the basis of the determination of the infinite dilution activity coefficient of phosphorus in silicon - the Henry's coefficient - as well as numerous gaseous species existing in the Si-P binary system. The lack of original calorimetric data is highlighted in view to a further more reliable description of the complete Si-P system.</div></div>","PeriodicalId":9436,"journal":{"name":"Calphad-computer Coupling of Phase Diagrams and Thermochemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.calphad.2024.102762
The γ + γ′ microstructure in novel Co-based superalloys is often obtained by means of alloying method. Therefore, this study focuses on exploring the evolution of the γ + γ′ microstructure through the addition of Zr using CALculation of PHAse Diagram (CALPHAD) method. The heat capacity of τ was experimentally determined by the sapphire method, and the enthalpy of formation of τ at 0 K was calculated using Density Functional Theory (DFT). The thermodynamic parameters were derived based on experimental results from phase equilibrium data and first-principles calculations using CALPHAD method. According to the thermodynamic analyses, the alloy Co80.0V18.5Zr1.5 (at. %) was homogenized at 1473 K for 10 h and aged at 1173 K for different time, the ordered L12-γ′ precipitates coarsened and dissolved after 2 h, and transformed into needle-like D019-Co3V after 67 h of aging, which indicated that the γ′ phase was not in a thermodynamically stable state in the Co–V–Zr system. If the stable γ′ phase is obtained, additional alloying elements is necessary to be added.
新型 Co 基超合金中的γ + γ′ 显微结构通常是通过合金化方法获得的。因此，本研究重点利用CALculation of PHAse Diagram（CALPHAD）方法探讨了添加Zr后γ+γ′微观结构的演变。τ的热容量通过蓝宝石法进行实验测定，τ在0 K时的形成焓则通过密度泛函理论（DFT）进行计算。热力学参数是根据相平衡数据的实验结果和使用 CALPHAD 方法进行的第一原理计算得出的。热力学分析表明，Co80.0V18.5Zr1.5（at. %）合金在 1473 K 下均质 10 h，在 1173 K 下老化不同时间后，有序的 L12-γ′ 沉淀在 2 h 后粗化并溶解，老化 67 h 后转变为针状的 D019-Co3V，这表明γ′相在 Co-V-Zr 体系中并不处于热力学稳定状态。如果要获得稳定的γ′相，就必须添加额外的合金元素。
{"title":"Study on the γ + γ′ microstructure characterization of the Co–V–Zr system based on CALPHAD method","authors":"","doi":"10.1016/j.calphad.2024.102762","DOIUrl":"10.1016/j.calphad.2024.102762","url":null,"abstract":"<div><div>The γ + γ′ microstructure in novel Co-based superalloys is often obtained by means of alloying method. Therefore, this study focuses on exploring the evolution of the γ + γ′ microstructure through the addition of Zr using CALculation of PHAse Diagram (CALPHAD) method. The heat capacity of τ was experimentally determined by the sapphire method, and the enthalpy of formation of τ at 0 K was calculated using Density Functional Theory (DFT). The thermodynamic parameters were derived based on experimental results from phase equilibrium data and first-principles calculations using CALPHAD method. According to the thermodynamic analyses, the alloy Co80.0V18.5Zr1.5 (at. %) was homogenized at 1473 K for 10 h and aged at 1173 K for different time, the ordered L1<sub>2</sub>-γ′ precipitates coarsened and dissolved after 2 h, and transformed into needle-like D0<sub>19</sub>-Co<sub>3</sub>V after 67 h of aging, which indicated that the γ′ phase was not in a thermodynamically stable state in the Co–V–Zr system. If the stable γ′ phase is obtained, additional alloying elements is necessary to be added.</div></div>","PeriodicalId":9436,"journal":{"name":"Calphad-computer Coupling of Phase Diagrams and Thermochemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.calphad.2024.102763
Thermal conductivity is one of the critical thermophysical properties for Al alloys. However, in comparison with mechanical properties, fewer studies focused on investigating thermal conductivity for Al alloys such as Al-Zn-Mg and its sub-systems. This study aims to combine experiments and modeling to assess thermal conductivity of FCC Al-Zn, Al-Mg and Al-Zn-Mg alloys. FCC Al-Zn, Al-Mg and Al-Zn-Mg alloys were first designed by CALPHAD (Calculation of PHAse Diagram) method. The alloy samples were prepared using the vacuum induction melting furnace, and their compositions and structures were validated via ICP (Inductively Coupled Plasma), XRD (X-ray diffraction) and SEM (Scanning Electron Microscope). Subsequently, LFA (Laser Flash Analysis) was applied to measure thermal conductivity of the presently prepared samples at 298, 348, 398, 448 and 498 K. Moreover, a novel model incorporated in CALTPP (CALculation of ThermoPhysical Properties) software was implemented for evaluating thermal conductivity of FCC Al-Zn, Al-Mg and Al-Zn-Mg alloys from 298 K to 498 K. All the deviations between the model-evaluated thermal conductivity and measured ones are within ±10 %, indicating that the present calculations are reliable. Furthermore, this work used this developed model to predict composition-dependent and temperature-dependent thermal conductivity for FCC Al-Zn, Al-Mg and Al-Zn-Mg alloys. The present work provides an effective way to investigate thermal conductivity for single-phase solid solutions combining experiments and modeling.
导热性是铝合金的关键热物理性质之一。然而，与机械性能相比，专注于研究 Al-Zn-Mg 等铝合金及其子系统导热性能的研究较少。本研究旨在结合实验和建模来评估催化裂化铝锌、铝镁和铝锌镁合金的导热性。首先采用 CALPHAD（PHAse Diagram 计算）方法设计了催化裂化铝锌、铝镁和铝锌镁合金。使用真空感应熔炉制备合金样品，并通过 ICP（电感耦合等离子体）、XRD（X 射线衍射）和 SEM（扫描电子显微镜）验证其成分和结构。此外，还在 CALTPP（热物理特性计算）软件中加入了一个新模型，用于评估催化裂化铝锌、铝镁和铝锌镁合金在 298 K 至 498 K 的热导率。模型评估的热导率与测量值之间的所有偏差都在±10%以内，表明本计算结果是可靠的。此外，本研究还利用所开发的模型预测了催化裂化铝锌、铝镁和铝锌镁合金随成分和温度变化的热导率。本研究提供了一种结合实验和建模研究单相固溶体热导率的有效方法。
{"title":"Assessment of thermal conductivity for FCC Al-X (X=Zn, Mg) and Al-Zn-Mg alloys: Experiments and modeling","authors":"","doi":"10.1016/j.calphad.2024.102763","DOIUrl":"10.1016/j.calphad.2024.102763","url":null,"abstract":"<div><div>Thermal conductivity is one of the critical thermophysical properties for Al alloys. However, in comparison with mechanical properties, fewer studies focused on investigating thermal conductivity for Al alloys such as Al-Zn-Mg and its sub-systems. This study aims to combine experiments and modeling to assess thermal conductivity of FCC Al-Zn, Al-Mg and Al-Zn-Mg alloys. FCC Al-Zn, Al-Mg and Al-Zn-Mg alloys were first designed by CALPHAD (Calculation of PHAse Diagram) method. The alloy samples were prepared using the vacuum induction melting furnace, and their compositions and structures were validated via ICP (Inductively Coupled Plasma), XRD (X-ray diffraction) and SEM (Scanning Electron Microscope). Subsequently, LFA (Laser Flash Analysis) was applied to measure thermal conductivity of the presently prepared samples at 298, 348, 398, 448 and 498 K. Moreover, a novel model incorporated in CALTPP (CALculation of ThermoPhysical Properties) software was implemented for evaluating thermal conductivity of FCC Al-Zn, Al-Mg and Al-Zn-Mg alloys from 298 K to 498 K. All the deviations between the model-evaluated thermal conductivity and measured ones are within ±10 %, indicating that the present calculations are reliable. Furthermore, this work used this developed model to predict composition-dependent and temperature-dependent thermal conductivity for FCC Al-Zn, Al-Mg and Al-Zn-Mg alloys. The present work provides an effective way to investigate thermal conductivity for single-phase solid solutions combining experiments and modeling.</div></div>","PeriodicalId":9436,"journal":{"name":"Calphad-computer Coupling of Phase Diagrams and Thermochemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-24DOI: 10.1016/j.calphad.2024.102757
The Nd-Sn phase diagram has been investigated within the range of 20–80 at.% Sn using X-ray diffraction (XRD), scanning electron microscope equipped with energy dispersive spectrometer (SEM-EDS), and differential scanning calorimetric (DSC). In addition to the nine known compounds, Nd5Sn3, Nd5Sn4, Nd11Sn10, NdSn, Nd3Sn5, NdSn2, Nd3Sn7, Nd2Sn5 and NdSn3, two reported compounds, Nd3Sn and Nd2Sn3, as well as two new compounds Nd2Sn and Nd4Sn5, have been detected. The formation of Nd2Sn, Nd4Sn5 and Nd2Sn3 has been determined as follows: Nd2Sn forms by peritectoid reaction Nd3Sn + Nd5Sn3 → Nd2Sn at 1134 °C; Nd4Sn5 and Nd2Sn3 form by peritectic reaction at 1168 °C and 1146 °C, respectively. Nd3Sn and Nd3Sn5 are only stable at high temperatures, Nd3Sn forms by a peritectic reaction at 1163 °C and decomposes at 1114 °C, and Nd3Sn5 is formed via a peritectic reaction at 1153 °C and decomposes at 1136 °C. Additionally, five invariant reaction temperature have been updated. The Nd-Sn system was modeled using the Calphad approach, incorporating new experimental data along with all other available experimental information. A comprehensive thermodynamic description of the Nd-Sn system has been obtained, and extensive comparisons between calculated and experimental data indicating that almost all adopted experimental and theoretical data are satisfactorily matched.
{"title":"Re-investigation the phase equilibria and thermodynamic assessment of the Nd-Sn binary system","authors":"","doi":"10.1016/j.calphad.2024.102757","DOIUrl":"10.1016/j.calphad.2024.102757","url":null,"abstract":"<div><div>The Nd-Sn phase diagram has been investigated within the range of 20–80 at.% Sn using X-ray diffraction (XRD), scanning electron microscope equipped with energy dispersive spectrometer (SEM-EDS), and differential scanning calorimetric (DSC). In addition to the nine known compounds, Nd<sub>5</sub>Sn<sub>3</sub>, Nd<sub>5</sub>Sn<sub>4</sub>, Nd<sub>11</sub>Sn<sub>10</sub>, NdSn, Nd<sub>3</sub>Sn<sub>5</sub>, NdSn<sub>2</sub>, Nd<sub>3</sub>Sn<sub>7</sub>, Nd<sub>2</sub>Sn<sub>5</sub> and NdSn<sub>3</sub>, two reported compounds, Nd<sub>3</sub>Sn and Nd<sub>2</sub>Sn<sub>3,</sub> as well as two new compounds Nd<sub>2</sub>Sn and Nd<sub>4</sub>Sn<sub>5</sub>, have been detected. The formation of Nd<sub>2</sub>Sn, Nd<sub>4</sub>Sn<sub>5</sub> and Nd<sub>2</sub>Sn<sub>3</sub> has been determined as follows: Nd<sub>2</sub>Sn forms by peritectoid reaction Nd<sub>3</sub>Sn + Nd<sub>5</sub>Sn<sub>3</sub> → Nd<sub>2</sub>Sn at 1134 °C; Nd<sub>4</sub>Sn<sub>5</sub> and Nd<sub>2</sub>Sn<sub>3</sub> form by peritectic reaction at 1168 °C and 1146 °C, respectively. Nd<sub>3</sub>Sn and Nd<sub>3</sub>Sn<sub>5</sub> are only stable at high temperatures, Nd<sub>3</sub>Sn forms by a peritectic reaction at 1163 °C and decomposes at 1114 °C, and Nd<sub>3</sub>Sn<sub>5</sub> is formed via a peritectic reaction at 1153 °C and decomposes at 1136 °C. Additionally, five invariant reaction temperature have been updated. The Nd-Sn system was modeled using the Calphad approach, incorporating new experimental data along with all other available experimental information. A comprehensive thermodynamic description of the Nd-Sn system has been obtained, and extensive comparisons between calculated and experimental data indicating that almost all adopted experimental and theoretical data are satisfactorily matched.</div></div>","PeriodicalId":9436,"journal":{"name":"Calphad-computer Coupling of Phase Diagrams and Thermochemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-22DOI: 10.1016/j.calphad.2024.102760
Solid oxide fuel cells (SOFCs) have garnered significant interest due to their potential as alternative electrical power generation systems that offer low pollutant emissions and high energy conversion efficiency. Neodymium silicates have emerged as promising electrolyte materials owing to their high ionic conductivity. To enhance our understanding of their performance in SOFC applications, it is essential to investigate the thermodynamic properties of neodymium silicates. In this study, we measured the heat capacities of the prepared samples over the temperature range of 673–1273 K using a multi-high temperature calorimeter (MHTC) 96 line. The temperature dependence of heat capacities for Nd2SiO5, Nd14Si9O39, and Nd2Si2O7 were modeled as functions: Cp(Nd2SiO5) = 194.7 + 0.028 T–4,714,800 T−2 – 239.75 T−0.5 + 491568400 T−3 (J·mol−1·K−1) (298.15 - 1400K), Cp(Nd14Si9O39) =1527.1 + 0.22 T − 40097000 T−2 – 2150.3 T−0.5 + 4424200000 T−3 (J·mol−1·K−1) (298.15 - 1400K), Cp(Nd2Si2O7) =276 + 0.032 T − 8261400 T−2 – 480 T−0.5 + 983136800 T−3 (J mol−1 K−1) (298.15–1400K), and then used for computing changes in entropy and Gibbs free energy. The Nd2O3-SiO2 system was reassessed based on the phase diagram experimental data and measured heat capacities in this work.
{"title":"Thermodynamic properties of neodymium silicates at high temperature (298.15–1273K) and thermodynamic reassessment of the Nd2O3-SiO2 system","authors":"","doi":"10.1016/j.calphad.2024.102760","DOIUrl":"10.1016/j.calphad.2024.102760","url":null,"abstract":"<div><div>Solid oxide fuel cells (SOFCs) have garnered significant interest due to their potential as alternative electrical power generation systems that offer low pollutant emissions and high energy conversion efficiency. Neodymium silicates have emerged as promising electrolyte materials owing to their high ionic conductivity. To enhance our understanding of their performance in SOFC applications, it is essential to investigate the thermodynamic properties of neodymium silicates. In this study, we measured the heat capacities of the prepared samples over the temperature range of 673–1273 K using a multi-high temperature calorimeter (MHTC) 96 line. The temperature dependence of heat capacities for Nd<sub>2</sub>SiO<sub>5</sub>, Nd<sub>14</sub>Si<sub>9</sub>O<sub>39</sub>, and Nd<sub>2</sub>Si<sub>2</sub>O<sub>7</sub> were modeled as functions: Cp<sub>(Nd2SiO5)</sub> = 194.7 + 0.028 T–4,714,800 T<sup>−2</sup> – 239.75 T<sup>−0.5</sup> + 491568400 T<sup>−3</sup> (J·mol<sup>−1</sup>·K<sup>−1</sup>) (298.15 - 1400K), Cp<sub>(Nd14Si9O39)</sub> =1527.1 + 0.22 T − 40097000 T<sup>−2</sup> – 2150.3 T<sup>−0.5</sup> + 4424200000 T<sup>−3</sup> (J·mol<sup>−1</sup>·K<sup>−1</sup>) (298.15 - 1400K), Cp<sub>(Nd2Si2O7)</sub> =276 + 0.032 T − 8261400 T<sup>−2</sup> – 480 T<sup>−0.5</sup> + 983136800 T<sup>−3</sup> (J mol<sup>−1</sup> K<sup>−1</sup>) (298.15–1400K), and then used for computing changes in entropy and Gibbs free energy. The Nd<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub> system was reassessed based on the phase diagram experimental data and measured heat capacities in this work.</div></div>","PeriodicalId":9436,"journal":{"name":"Calphad-computer Coupling of Phase Diagrams and Thermochemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-15DOI: 10.1016/j.calphad.2024.102759
Pressure can affect phase diagrams significantly, as previously demonstrated on several binary systems. However, the effect of pressure on ternary phase diagrams is mostly unexplored. In this study, a thermodynamic model of a ternary phase diagram under high pressure is formulated and applied to calculate the Bi-Sb-Pb system. The model employs binary interaction parameters and elemental thermodynamic functions to which the effect of pressure on the binary interaction parameters and elemental properties are added. The complete ternary Bi-Sb-Pb phase diagram was calculated up to a pressure of 2 GPa at selected temperatures as a case study, as this system involves three different types of binary phase diagrams: isomorphous, eutectic, and peritectic. The results show how pressure affects the stability of solid phases, leading to changes in the three-phase triangles and the four-phase equilibrium quadrilateral. This study provides insights into the pressure-dependent behavior of ternary systems and contributes to the thermodynamic understanding of ternary phase diagrams under high-pressure conditions.
{"title":"Pressure effect on ternary phase diagrams: Bi-Sb-Pb as a case study","authors":"","doi":"10.1016/j.calphad.2024.102759","DOIUrl":"10.1016/j.calphad.2024.102759","url":null,"abstract":"<div><div>Pressure can affect phase diagrams significantly, as previously demonstrated on several binary systems. However, the effect of pressure on ternary phase diagrams is mostly unexplored. In this study, a thermodynamic model of a ternary phase diagram under high pressure is formulated and applied to calculate the Bi-Sb-Pb system. The model employs binary interaction parameters and elemental thermodynamic functions to which the effect of pressure on the binary interaction parameters and elemental properties are added. The complete ternary Bi-Sb-Pb phase diagram was calculated up to a pressure of 2 GPa at selected temperatures as a case study, as this system involves three different types of binary phase diagrams: isomorphous, eutectic, and peritectic. The results show how pressure affects the stability of solid phases, leading to changes in the three-phase triangles and the four-phase equilibrium quadrilateral. This study provides insights into the pressure-dependent behavior of ternary systems and contributes to the thermodynamic understanding of ternary phase diagrams under high-pressure conditions.</div></div>","PeriodicalId":9436,"journal":{"name":"Calphad-computer Coupling of Phase Diagrams and Thermochemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142442392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-13DOI: 10.1016/j.calphad.2024.102755
Dental amalgam, known for its biocompatibility and ductility, is widely used in restorative materials. In dental crown restorations, studying the interactions between amalgam fillings and crown tissues, particularly the roles of calcium (Ca) and strontium (Sr), is essential for improving function stability and biocompatibility. This study conducts critical literature evaluation and thermodynamic optimization of binary systems involving mercury (Hg) with Ca and Sr, focusing specifically on their suitability for dental amalgam restoration. Using first-principles calculations (FPC), the enthalpies of formation for compounds within the Hg-Ca and Hg-Sr binary systems were calculated in this work. Thermodynamic modeling of the liquid solution employed the modified quasichemical model in the pair approximation (MQM), uncovering significant short-range ordering. Conversely, solid phases were modeled using the compound energy formalism (CEF). The incorporation of FPC proves to be a valuable and effective method, providing essential insights to complement the calculation of phase diagrams (CALPHAD) modeling approach. Ultimately, this research significantly enhances our understanding of the thermodynamic characteristics of Hg-X alloys, with notable implications for their potential application in dental amalgam restoration.
{"title":"Thermodynamic study on the phase diagram of the Hg-Ca and Hg-Sr binary systems for dental amalgam restoration application","authors":"","doi":"10.1016/j.calphad.2024.102755","DOIUrl":"10.1016/j.calphad.2024.102755","url":null,"abstract":"<div><div>Dental amalgam, known for its biocompatibility and ductility, is widely used in restorative materials. In dental crown restorations, studying the interactions between amalgam fillings and crown tissues, particularly the roles of calcium (Ca) and strontium (Sr), is essential for improving function stability and biocompatibility. This study conducts critical literature evaluation and thermodynamic optimization of binary systems involving mercury (Hg) with Ca and Sr, focusing specifically on their suitability for dental amalgam restoration. Using first-principles calculations (FPC), the enthalpies of formation for compounds within the Hg-Ca and Hg-Sr binary systems were calculated in this work. Thermodynamic modeling of the liquid solution employed the modified quasichemical model in the pair approximation (MQM), uncovering significant short-range ordering. Conversely, solid phases were modeled using the compound energy formalism (CEF). The incorporation of FPC proves to be a valuable and effective method, providing essential insights to complement the calculation of phase diagrams (CALPHAD) modeling approach. Ultimately, this research significantly enhances our understanding of the thermodynamic characteristics of Hg-X alloys, with notable implications for their potential application in dental amalgam restoration.</div></div>","PeriodicalId":9436,"journal":{"name":"Calphad-computer Coupling of Phase Diagrams and Thermochemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-30DOI: 10.1016/j.calphad.2024.102739
Nickel-based superalloys are extensively utilized in aerospace engines, marine gas turbines, and other environments with severe operating conditions. The phase relations of the Ni-Mo-Y ternary system were experimentally studied across the entire composition range at 800 °C and 1000 °C using scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Thirteen three-phase regions were confirmed at 800 °C, and eleven three-phase regions were observed at 1000 °C. No ternary compound was observed at these temperatures. In addition, the experimental results indicate that molybdenum (Mo) has almost no solubility in the binary compounds found in the Ni-Y binary system. Furthermore, the primary solidification phases and the solidification process of typical alloys were investigated, and three different primary solidification phases were found. Based on the experimental results, thermodynamic calculations for the Ni-Mo-Y system were performed through the CALPHAD technique. The experimental results agree well with the calculated, a set of self-consistent thermodynamic parameters for the Ni-Mo-Y ternary system was obtained in the present work.
镍基超级合金广泛应用于航空航天发动机、船用燃气轮机和其他工作条件恶劣的环境中。利用扫描电子显微镜 (SEM)、能量色散光谱 (EDS) 和 X 射线衍射 (XRD)，在 800 °C 和 1000 °C 的整个成分范围内对 Ni-Mo-Y 三元体系的相关系进行了实验研究。在 800 °C 时确认了 13 个三相区域，在 1000 °C 时观察到 11 个三相区域。在这些温度下均未观察到三元化合物。此外，实验结果表明，钼（Mo）几乎不溶于镍-钇二元体系中的二元化合物。此外，还研究了典型合金的初级凝固相和凝固过程，发现了三种不同的初级凝固相。根据实验结果，通过 CALPHAD 技术对 Ni-Mo-Y 体系进行了热力学计算。实验结果与计算结果吻合良好，从而获得了一套自洽的 Ni-Mo-Y 三元体系热力学参数。
{"title":"Experimental investigation and thermodynamic description of the Ni-Mo-Y ternary system","authors":"","doi":"10.1016/j.calphad.2024.102739","DOIUrl":"10.1016/j.calphad.2024.102739","url":null,"abstract":"<div><div>Nickel-based superalloys are extensively utilized in aerospace engines, marine gas turbines, and other environments with severe operating conditions. The phase relations of the Ni-Mo-Y ternary system were experimentally studied across the entire composition range at 800 °C and 1000 °C using scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Thirteen three-phase regions were confirmed at 800 °C, and eleven three-phase regions were observed at 1000 °C. No ternary compound was observed at these temperatures. In addition, the experimental results indicate that molybdenum (Mo) has almost no solubility in the binary compounds found in the Ni-Y binary system. Furthermore, the primary solidification phases and the solidification process of typical alloys were investigated, and three different primary solidification phases were found. Based on the experimental results, thermodynamic calculations for the Ni-Mo-Y system were performed through the CALPHAD technique. The experimental results agree well with the calculated, a set of self-consistent thermodynamic parameters for the Ni-Mo-Y ternary system was obtained in the present work.</div></div>","PeriodicalId":9436,"journal":{"name":"Calphad-computer Coupling of Phase Diagrams and Thermochemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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