基于原子-分子共存理论的全浓度Ti-Al二元熔体热力学性质计算（英文）

基于原子-分子共存理论建立计算温度为1973~2273 K及全浓度范围Ti-Al二元熔体质量作用浓度Ni的热力学模型。利用不同温度(1973、2073、2173和2273 K)下的模型计算结果,得到在无限稀溶液(0x_(Ti)0.01)中铝、钛活度因子的对数与温度的关系式。根据该表达式,进一步得到组元i溶解于Ti-Al二元熔体形成浓度为1%(质量分数)溶液为标准态的溶解Gibbs自由能。与此同时,对Ti-Al二元熔体的过剩Gibbs自由能、过剩熵、过剩焓也进行了计算。     

基于Miedema模型和Toop模型的Al-Si-Er合金热力学参数计算

运用Miedema混合焓模型计算了Al-Er、Si-Er和Al-Si二元合金的部分热力学性质,选择Er为非对称性组元,在此基础上结合Toop模型计算出Al-Si-Er三元合金的混合焓、过剩熵与过剩自由能。结果表明,Al-Si-Er三元合金的混合焓、过剩熵与过剩自由能在整个浓度范围内均为负值,在富Er和贫Er区域各热力学参数变化趋势较大。通过计算Al、Si和Er 3种组元的偏摩尔过剩自由能得到Al-Si-Er三元合金各组元的等活度值曲线。曲线显示各组元随着摩尔分数的减少其活度值都急剧减小,在三元系成分三角形的中心部分Al、Si和Er的活度值都很小,这表明Al、Si和Er 3种组元之间存在很强的相互作用,易形成三元金属间化合物,这一结论与Al-Si-Er三元相图的实际情况相符合。     

Al-Er和Si-Er二元合金的热力学性质

以Miedema混合焓模型为基础,计算Al-Er和Si-Er二元合金的部分热力学函数,如混合焓-H,过剩熵SE以及过剩吉布斯自由能GE以及各组元的活度.结合Al-Er和Si-Er二元相图计算了Al3Er和Er5Si3相析出反应的吉布斯自由能.结果表明:Al-Er和Si-Er二元合金的混合焓、过剩自由能与过剩熵在整个浓度范围内均为负值,各组元活度计算结果相对于理想熔体有较大的负偏差,说明Er原子与Al原子和Si原子都有很强的相互作用; Al3Er和Er5Si3相反应的吉布斯自由能均为负值,且Er5Si3相的反应吉布斯自由能比Al3Er相的小,因此Er加入到Al-Si合金中会优先与Si生成Er5Si3相,过剩的Er才与Al生成Al3Er相.     

Al-Mg合金热力学性质的计算

以Ｍｉｅｄｅｍａ二元合金生成热模型为基础,结合一些基本热力学关系式,利用元素的基本性质计算了１０７３Ｋ下ＡｌＭｇ合金中组元Ｍｇ的活度及合金的部分热力学函数（ΔＨ,ＧＥ,ＳＥ）。结果表明,在１０７３Ｋ下,溶液中Ｍｇ的行为相对拉乌尔定律存在较大的负偏差;混合焓、过剩自由能与过剩熵在整个浓度范围内均为负值;混合焓最小值为－１１．４ｋＪ／ｍｏｌ,过剩自由能最小值为－８．７７ｋＪ／ｍｏｌ,过剩熵的绝对值较小,接近零。计算结果与实验数据吻合较好。     

Zn—Mn和Zn—Ti二元合金热学性质

在考虑理论计算合金形成热的各种影响因素的基础上,用Miedeman二元合金生成热模型计算了彩色热镀锌用Zn-Mn和Zn-Ti二元溶液的混合焓△Hmix与添加元素的摩尔分数之间的关系,利用Tanaka近似关系式及一些基本热力学关系计算了上述两个二元体系的过剩混合熵△G^Emix及各组元的活度,结果表明,Zn-Mn和Zn-Ti两溶相对于理想溶液都有很大的负偏差。     

Fe-Cu-C和Fe-Cu-Co-C熔体的热力学性质

本文测得碳在Fe-Cu-C和Fe-Cu-Co-C系中的溶解度和分层数据,计算这些体系中Cu和Fe的活度系数以及碳对Cu和Fe活度系数的影响。结果表明,随着体系中碳量的增加,相应地Cu活度系数增加,而Fe活度系数减少。在这些数据的基础上,还计算了Fe-Cu-C系的一级、二级活度相互作用系数,等活度时自由能相互作用系数和焓相互作用系数,并估计了Cu量对碳溶解过剩焓的影响。计算结果与其它已报道的Fe-j-C系相比较,发现这些热力学性质与原子序数之间有一定的规律。     

THERMODYNAMIC PROPERTIES OF Fe-Cu-C AND Fe-Cu-Co-C MELTS

本文测得碳在Fe-Cu-C和Fe-Cu-Co-C系中的溶解度和分层数据,计算这些体系中Cu和Fe的活度系数以及碳对Cu和Fe活度系数的影响。结果表明,随着体系中碳量的增加,相应地Cu活度系数增加,而Fe活度系数减少。在这些数据的基础上,还计算了Fe-Cu-C系的一级、二级活度相互作用系数,等活度时自由能相互作用系数和焓相互作用系数,并估计了Cu量对碳溶解过剩焓的影响。计算结果与其它已报道的Fe-j-C系相比较,发现这些热力学性质与原子序数之间有一定的规律。     

In-Bi-Tl三元系液体合金中成分的活度测定SCIEI

用ZrO_2固体电解质组成氧浓差电池:(-)Re,In,In_2O_3|ZrO_2(Y_2O_3)|In-Bi-Tl,In_2O_3,Re(+),在973—1223K的温变范围内测定了In-Bi-Tl三元系中含Tl量较少的两个mol比(N_(Bi)/N_(Tl))一定的拟二元系合金中In的活度,据实验结果求得合金的过剩自由能。使用作者曾提出的计算式及有关各二元系热力学数据计算了合金中In的活度及过剩自由能。计算值与实验值相当一致。此三元系合金的过剩自由能除在In-Tl二元系相近组成以外都呈负值,极小值在Bi-Tl二元系上。     

镍基粉末合金中碳化物的析出行为及热力学分析

利用Miedema和Toop热力学模型计算粉末镍基合金中碳化物的生成热、活度系数及NbC、TiC碳化物的过剩Gibbs自由能,进一步求出合金中析出NbC、TiC碳化物的Gibbs自由能与温度的关系式,研究粉末镍基合金中碳化物的析出行为.结果表明,在实验温度范围内,合金中可析出NbC、TiC碳化物,并确定出合金中NbC、TiC碳化物相的析出温度分别为1353 K和1090 K,由于Ti、Nb晶体结构的相似性,碳化物中两原子可相互置换,并以(Ni,Ti)C型线性碳化物形式存在.     

共晶高熵合金形成的热力学基础研究

通过收集并总结已报道的18种共晶高熵合金的整体成分和各相成分等信息分别计算了反映其性质的一些参数,包括混合焓、混合熵、吉布斯自由能、原子尺寸失配度、电负性差和价电子数,并从热力学角度分析了这些参数对合金结构的影响规律。发现共晶高熵合金整体成分计算出的混合熵等值均基本满足传统高熵合金形成单相固溶体的结构判据要求(即?Smix11 J/(mol×K)、-15 kJ/molΔH_(mix) 5 kJ/mol,δ6.6%等),但是由于其共晶相的平均自由能低于其整体形成单相时的总自由能,这使得共晶高熵合金在凝固过程中发生共晶反应,形成多相结构。     

U基二元熔体的热力学计算

采用Miedema半经验模型计算了U-Nb、U-Ti及U-Zr二元熔体的混合热、过剩熵及过剩自由能等热力学性质,并根据热力学原理计算了组元U在不同温度的二元熔体中的活度值.结果表明,U-Nb,U-Ti和U-Zr熔体相对于拉乌尔定律均呈负偏差,U-Ti和U-Zr合金较U.Nb合金更易于形成中间化合物.计算结果与实验相图符合较好.     

Contributions to the modelling of the thermodynamic behaviour of Se---Te liquid solutions

The contributions from the changes in volume which occur on isothermally mixing at constant pressure, or excess volume, in the analytical formulation of the difference between the thermodynamic quantities of mixing, such as enthalpy, entropy and Gibbs free energy, derived at constant volume and those derived at constant pressure are considered. The procedure followed is to express this difference in a power series expansion, in terms of the excess volume. Numerical calculations are performed to assess the effect of the excess volume on the thermodynamic mixing quantities. Finally, the treatment is applied to the calculation of the thermodynamic mixing quantities of Se---Te liquid alloys at 773 K. The analysis shows that the agreement between the calculated and the experimental data is significantly improved when the excess volume contributions are considered.     

Determination of thermodynamic properties in full composition range of Ti-Al binary melts based on atom and molecule coexistence theory

The results of predicting thermodynamic properties in the full composition range of Ti-Al binary melts in a temperature range from 1973 to 2273 K were obtained by coupling with the developed thermodynamic model for calculating mass action concentration N_i of structural units in Ti-Al system based on the atom and molecule coexistence theory (AMCT). Temperature dependence of the activity coefficients of Ti and Al in natural logarithmic form in the infinitely dilute solution (0>x_Ti<0.01) of Ti-Al binary melts was also determined from the calculated activity coefficients of Ti and Al at temperatures of 1973, 2073, 2173, and 2273 K. The standard molar Gibbs free energy change of dissolving pure liquid element i(l) for forming 1% (mass fraction) element i in Ti-Al binary melts further was deduced. With the aid of this model, meanwhile, the determined excess thermodynamic properties, such as the excess molar mixing Gibbs free energy/entropy/enthalpy were also calculated.     

Calorimetric and Electromotive Force Measurements of Al-Li-Zn Liquid Solutions

The solution calorimetry and electromotive force methods were used for the study of the mixing enthalpy and partial excess Gibbs energy of the Al-Li-Zn liquid solutions. Calorimetric investigations were conducted for solutions with the ratio of X _Li/X _Al and X _Li/X _Zn = 0.8/0.2 and at the temperatures of 942 and 978 K, respectively. The electromotive force studies were performed at two temperatures: 873 and 923 K by the titration technique and for dilute solutions. Based on the data of the mixing enthalpy change and the partial excess Gibbs energy of Li available in the literature, together with that obtained in these studies, the ternary interaction parameters were elaborated. The comparative analysis of the experimental mixing enthalpy change generally showed a good agreement with the values calculated based on different models. The observed deviations between the experimental and the calculated values were, for most of the experimental data, lower than 1 kJ/mol. The experimental partial excess Gibbs energy of Li showed a satisfactory agreement with that modeled on the basis of the ternary parameters elaborated in this work.     

第一性原理研究Re的热力学性质

基于准谐Debye-Grüneisen模型,运用第一性原理缀加投影平面波方法研究了Re的热力学性质,拟合了Re的状态方程,计算了Re不同压强下弹性模量、吉布斯自由能、焓、熵、热容和体膨胀系数随温度的变化关系。结果表明:采用八阶Birch-Murnaghan方程拟合得到的Re压强-体积曲线与实验测量结果吻合较好;计算的零压下吉布斯自由能、焓、熵、热容和体膨胀系数随温度的变化均与实验值符合较好;在零压,50、100、150和200GPa压强下,Re的弹性模量和吉布斯自由能随温度升高而减小;焓、熵随温度升高而增加;Re的电子等容热容随温度线性增加,晶格振动等容热容在低温下符合3T幂次规律并随温度增加而迅速增大,且在高温时逐渐接近Dulong-Petit极限;预测的德拜温度约为430K,与实验结果一致。     

Thermodynamic Evaluation of Yttrium

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Electronic theory of phase stability in substitutional alloys: application to the Au–Ni system

The total energies of formation of Au–Ni superstructures based on a fcc lattice have been calculated using the linear muffin-tin-orbital (LMTO) method in the full potential approach. Both unrelaxed and relaxed structures have been included in the calculations. The energy of formation is decomposed into three terms, a volume deformation contribution, a chemical contribution and a relaxation contribution. The enthalpy of mixing of the disordered solid solution has been calculated using an Ising-like cluster expansion for both the chemical and relaxation effects. In the Gibbs energy of mixing, a configurational entropy of mixing has been calculated with the cluster variation method (CVM) and the thermal excitations due to electronic and vibrational effects have been taken into account. The miscibility gap displayed in the Au–Ni system has been calculated. The results are discussed in comparison with the experimental data.     

Thermodynamic investigation on the si-ge binary system by calorimetry and knudsen cell mass spectrometry

The partial enthalpy of Si in Si-Ge liquid alloys was determined by drop calorimetry at 1327 K in the 0 < Xsi< 0.03 concentration range with a high-temperature Calvet calorimeter. The excess Gibbs energy of formation of the melt was derived from Knudsen cell mass spectrometric measurements over the entire range of composition using the intensity ratio method. The thermodynamic behavior of the liquid phase of the system is regular and presents positive deviations from ideal mixing. It corresponds to the following thermodynamic functions for the melt: G^ex = 6.0XSiXGe kj/mol at 1723 K; and H^ex = 6.61XSiXGe kj/mol. The phase diagram calculated assuming such a behavior agrees well with the data of the literature. Some liquidus points obtained from the breaks existing in the logarithm of the vapor pressure versus the inverse temperature plots also agree.