Al-Si-Fe合金熔体质量作用浓度的热力学模型

基于原子分子共存理论(AMCT)建立了计算Al-Si二元熔体及Al-Si-Fe三元熔体结构单元质量作用浓度的热力学模型。针对Al-Si二元系熔体,根据FactSage热力学软件计算的活度得到生成复杂分子Al_2Si和AlSi的反应的标准摩尔吉布斯自由能的表达式,进而获得了Al-Si二元熔体中标准摩尔溶解吉布斯能变的表达式。同时建立了Al-Si-Fe三元系熔体的质量作用浓度计算模型,并与文献报道的结果对比。结果表明:1 673～1 873 K下在全浓度范围内计算得到的Al-Si和Al-Si-Fe熔体的质量作用浓度与前人报道的数据吻合良好。     

基于原子和分子共存理论的Al--Ti熔体反应能力表征

基于原子和分子共存理论建立计算Al-Ti二元合金系结构单元质量作用浓度的热力学模型.利用文献报道的2073、2173和2273 K下Al-Ti二元系的活度计算了生成Al₃Ti、AlTi和Al₁₁Ti₅反应的平衡常数,并进一步得到其标准摩尔吉布斯自由能的表达式.使用文献报道的不同温度下Al-Ti二元合金系全浓度范围内组元Al和Ti的活度a_Al和a_Ti与原子和分子共存理论定义的质量作用浓度N_Al和N_Ti进行比较.结果表明:在Al-Ti二元合金熔体全浓度范围内计算得到的质量作用浓度N_Al和N_Ti与文献报道的活度符合很好.同时,计算得到的Al-Ti二元合金系中结构单元Al₃Ti和Al₁₁Ti₅的平衡物质的量与其质量作用浓度的关系呈"棒状",而结构单元AlTi的平衡物质的量与其质量作用浓度的关系呈"纺锤"形.      

基于原子-分子理论的二元合金熔体热力学计算

分别使用Miedema、MIVM、NRTL、Wilson二元合金系热力学模型及FactSage热力学软件计算Bi-Pb、Bi-Sn、Cd-Pb、Pb-Sn 4个二元合金系的活度值,并与实验值进行比较.结果表明:Miedema、MIVM、NRTL、Wilson模型计算不同体系活度的效果不同,每种模型都有其适用的体系.而FactSage热力学软件计算的活度均与实验值吻合较好,文中使用FactSage分别计算Bi-Pb、Bi-Sn、Cd-Pb、Pb-Sn 4个二元系不同温度下的活度值.同时利用原子-分子理论计算Bi-Pb二元系质量作用浓度,给出生成金属间化合物BiPb反应的标准吉布斯自由能的表达式.      

含钡二元合金熔体热力学性质的计算

根据Miedema二元合金生成热模型，结合相关热力学数据，对Si-Ca二元合金熔体在1623K时的组元活度进行了计算，计算结果与实测结果吻合较好。并进一步对Ba-Si、Ba-Al和Ba-Ca3种二元含钡合金熔体的生成热△H及1873K时的过剩熵S^E、过剩自由能G^E以及不同温度下各组元的活度等热力学性质进行了计算。结果表明：3种合金的△H、S^E和G^E均为负值，且S^E绝对值的最大值为4．424J／mol，可以近似认为3种合金熔体的S^E为零；Ba-Si和Ba-Al合金熔体的活度相对于理想溶液存在较大负偏差，而Ba-Ca合金熔体的活度与理想溶液偏差较小。     

铝热法制备钒铝合金热力学及动力学研究

基于原子-分子理论建立了计算Al-V二元合金系结构单元质量作用浓度的热力学模型。利用文献报道的2 000、2 073、2 173、2 273 K下Al-V二元系的活度计算了生成Al8V5、Al4V反应的平衡常数,并进一步得到其摩尔标准吉布斯自由能的表达式。同时采用TG-DSC热重同步热试验分析的方法,研究了不同升温速率下,铝热法合成钒铝合金反应机理及化学反应动力学。结果发现温度在660~690℃时,差示扫描量热曲线各出现一个吸热、放热峰,说明反应机理已发生改变。然后分别运用Kissinger法、Kissinger-Crane法求解铝热反应动力学参数,建立动力学方程,通过动力学计算得到表观活化能E=448.96 k J/mol,频率因子A=1.98×10~(29)m/s,反应级数n=0.83。     

碳饱和三元金属熔体热力学性质的计算方法

为了简化金属熔体热力学性质的计算过程和获得任意温度下熔体组元的热力学性质，基于一种碳饱和三元金属熔体热力学性质的计算方法，将三元金属熔体中碳的饱和溶解度分解为温度T和第三组元j的影响因子kj(或mj)两项，得到用T和kj(或mj)表示的组元活度相互作用系数的计算公式。用该公式可以计算出M—C-j三元熔体中组元j在任意温度下的活度相互作用系数，并可得到组元j的活度相互作用系数与温度的关系式。将计算的Fe-C—Cr体系和Mn—C—Fe体系的性质应用于热力学分析，获得了与实际生产比较吻合的结果。     

合金熔体结构和原子- 分子热力学模型

对金属熔体结构的研究证实熔体中存在短程有序结构,而含金属间化合物的合金熔体中发现了原子- 分子结合的团簇结构,即固态下的金属间化合物在熔体中并没有消失,而是以团簇结构（实际上就是液态的分子）存在,并与熔体中的自由原子存在化学平衡。从熔体结构出发,提出了适用于合金熔体的原子- 分子热力学模型。然后以Ca- Mg合金熔体为例,介绍了该模型的构建和求解方法,并计算了1010K下的Ca- Mg合金熔体中各物质的摩尔分数。最后,将计算得到的钙、镁摩尔分数与各自的实测活度值进行比较,发现两者吻合得较好。这从计算上证明了合金熔体中同时存在着金属原子和金属间化合物分子,两者处于动态化学平衡之中。且达到平衡时,金属原子的摩尔分数实际上就是各自的活度。因此,对于合金熔体而言,活度并不存在。     

冰铜吹炼过程的热力学分析

本文采用缔合容液模型计算了 Cu-Fe-S 三元熔体的热力学性质,分析了冰铜吹炼过程、的热力学平衡。     

碳在纯锰和纯铁熔体中的饱和溶解度及Mn-Fe-C熔体的热力学性质

根据不同温度下Ｃ在纯Ｆｅ和纯Ｍｎ熔体中的饱和溶解度数据,分别得到Ｃ的饱和溶解度与温度的关系式,利用两个关系式可以直接计算Ｆｅ－Ｃ－Ｍｎ和Ｍｎ－Ｃ－Ｆｅ三元熔体组元的热力学性质,同利用Ｃ在这两种熔体中的饱和溶解度实验数据计算出的熔体组元的热力学性质非常接近。     

MNO_3–Ca(NO_3)_2 (M=Li,Na,K)二元相图的热力学优化

基于CALPHAD方法对MNO3-Ca(NO3)2(M=Li,Na,K)二元相图的试验数据首次进行了热力学优化拟合,得到了3个二元相图的过量混合热力学性质的参数及Ca(NO3)2的熔化吉布斯自由能随温度变化的函数表达式,并用拟合的参数计算了3个二元相图,最后将计算得到的相图与试验相图进行了比较。     

Al—Si—Fe三元合金熔体组元活度的解析

将Ａｌ－Ｓｉ－Ｆｅ三元合金熔体中组元Ａｌ的过剩偏摩尔自由能表达成多项式函数的形式,再由组成该三元系的三个二元子系以及三元系部分实验结果作为边界条件确定多项式中的参数Ａｊｋ值。根据Ｇｉｂｂｓ－Ｄｕｈｅｍ方程导出了计算体系过剩摩尔自由能多项式中的参数Ｆｊｋ值,由Ａｊｋ和Ｆｊｋ值求得组元Ｓｉ、Ａｌ的过剩偏摩尔自由能的表达式,并用上述解析表达式计算出了整个液相区域内各组元的等活度线     

A Thermodynamic Model for Representation Reaction Abilities of Structural Units in Full Composition Range of Fe–Si Binary Melts Based on the Atom–Molecule Coexistence Theory

A thermodynamic model for calculating the mass action concentrations of structural units in Fe–Si binary melts based on the atom–molecule coexistence theory, i.e., the AMCT–N_i model, has been developed and verified through comparing with the reported activities of both Si and Fe in the full composition range of Fe–Si binary melts at temperatures of 1693, 1773, 1873, and 1973 K from the literature. The calculated mass action concentration N_Si of free Si or N_Fe of free Fe in the full composition range of Fe–Si binary melts has a good 1:1 corresponding relationship with the reported activity a_R,Si of Si or a_R,Fe of Fe relative to pure liquid Si(l) or Fe(l) as standard state. The calculated mass action concentration N_Si of free Si has a good corresponding relationship with the calculated activity a_%,Si of Si referred to 1 mass% of Si as standard state as well as the calculated activity a_H,Si of Si relative to the hypothetical pure liquid Si(l) as standard state. The calculated activity a_%,Si or a_H,Si of Si is much greater than the calculated mass action concentration N_Si of free Si in Fe–Si binary melts. The reaction abilities of both Si and Fe show a competitive or coupling relationship in Fe–Si binary melts at the above‐mentioned four temperatures. The calculated mass action concentrations N_i of six structural units as Fe, Si, Fe₂Si, Fe₅Si₃, FeSi, and FeSi₂ cannot show the linear relationship with the calculated equilibrium mole numbers n_i in 100‐g Fe–Si binary melts simultaneously. A spindle‐type relationship between the calculated mass action concentration N_i and the calculated equilibrium mole number n_i of FeSi and FeSi₂ in Fe–Si binary melts has been found.     

A Thermodynamic Model for Representation Reaction Abilities of Structural Units in Fe-S Binary Melts Based on the Atom-Molecule Coexistence Theory

A thermodynamic model for calculating the mass action concentrations of structural units in Fe-S binary melts based on the atom-molecule coexistence theory, i.e., AMCT-N _i model, has been developed and verified through a comparison with the reported activities of both S and Fe in Fe-S binary melts with changing mole fraction $ x_{\text{S}} $ of S from 0.0?to 0.095?at temperatures of 1773?K, 1823?K, and 1873?K (1500 °C, 1550 °C, and 1600 °C) from the literature. The calculated mass action concentration $ N_{\text{S}} $ of S is much smaller than the reported activity $ a_{\text{R, S}} $ of S in Fe-S binary melts with changing mole fraction $ x_{\text{S}} $ of S from 0.0?to 0.095. The calculated mass action concentration $ N_{\text{S}} $ of S can correlate the reliable 1:1?corresponding relationship with the reported activity $ a_{\text{R, S}} $ or $ a_{\%,\text {S}} $ of S through the introduced transformation coefficients with absolutely mathematical meaning or through the defined comprehensive mass action concentration of total S with explicitly physicochemical meaning. The calculated mass action concentrations $ N_{i} $ of structural units from the developed AMCT-N _i thermodynamic model can be applied to describe or predict the reaction abilities of structural units in Fe-S binary melts. The reaction abilities of Fe and S show a competitive relationship each other in Fe-S binary melts in a temperature range from 1773?K to 1873?K (1500 °C to 1600 °C). The calculated mass action concentration $ N_{{{\text{FeS}}_{ 2} }} $ of FeS_2?is very small and can be ignored because FeS_2?can be incongruently decomposed above 1016?K (743 °C). The very small values for the calculated mass action concentrations $ N_{{{\text{FeS}}_{ 2} }} $ of FeS_2?in a range of mole fraction $ x_{\text{S}} $ of S from 0.0?to 1.0?as well as a maximum value for the calculated mass action concentration $ N_{\text{FeS}} $ of FeS with mole fraction $ x_{\text{S}} $ of S as 0.5?are coincident with diagram phase of Fe-S binary melts. A spindle-type relationship between the calculated mass action concentration $ N_{i} $ and the calculated equilibrium mole number $ n_{i} $ can be found for FeS and FeS_2?in Fe-S binary melts. The Raoultian activity coefficient $ \gamma_{S}^{0} $ of S relative to pure liquid S(l) as standard state and the infinitely dilute solution as reference state in Fe-S binary melts can be determined as 1.0045?in a temperature range from 1773?K to 1873?K (1500 °C to 1600 °C). The standard molar Gibbs free energy change $ \Updelta_{\text{sol}} G_{{{\text{m, S }}({\text{l}}) \to [{\text{S}}]_{{ \, [{\text{pct \, S}}] = 1.0}} }}^{{\Uptheta,\%}} $ of dissolving liquid S for forming [pct S] as 1.0?in Fe-S binary melts relative to 1?mass percentage of S as standard state can be formulated as $ \Updelta_{\text{sol}} G_{{{\text{m, S }}({\text{l}}) \to [{\text{S}}]_{{ \, [{\text{pct \, S] }} = \, 1.0}} }}^{{\Uptheta,\, \%}} \,\, = -0.219\,-\,33.70T\,\,\left( {\text{J/mol}} \right).$      

Estimation of the viscosities of binary metallic melts using Gibbs energies of mixing

In the present work, information on the integral molar Gibbs energies of mixing is employed to calculate the viscosities of binary substitutional metallic melts. A correlation has been established between the second derivative of the integral molar Gibbs energy of mixing with respect to composition and the corresponding function for the Gibbs energy of activation for viscosity. The viscosities predicted from available thermodynamic data in the case of a number of binary metallic systems using this correlation show satisfactory agreement with the values reported from experimental measurements. The value of this correlation in predicting the viscosities of complex metallic melts is also examined.     

基于不同模型的硅铁熔体热力学性质计算

采用熔体热力学模型计算熔体热力学性质是冶金物理化学研究的重要内容。基于Miedema模型和作用浓度模型对硅铁熔体混合焓和活度进行了计算,并与其他模型计算结果及实测数据进行了对比分析。计算结果表明,Miedema模型相对于作用浓度模型的混合焓计算结果与实测值差距较小。采用作用浓度模型计算硅铁活度时,需要依据已有的活度数据拟合得到硅铁金属间化合物的生成? 妓棺杂赡埽也捎没疃饶夂系玫降墓杼鹗艏浠衔锷勺杂赡苡胧匝橹挡罹嘟洗蟆６砸延腥攘ρＰ偷慕峁员确治霰砻鳎匀厶逦⒐劢峁沟淖既范棵枋鍪墙⑽锢硪庖迩逦夷茏既吩けㄈ厶逍灾实娜攘ρЪ扑隳Ｐ偷墓丶?     

Application of Annexation Principle in Investigation of Thermodynamic Property of Ternary Metallic Melt Fe-Cr-Ni

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Composition and thermodynamics of the surface layer of binary melts based on iron,cobalt, and nickel

The composition, thickness, thermodynamic activities of components, Gibbs energy and excess energy of formation of the surface layer on binary melts of iron, cobalt and nickel-based alloys with different interatomic interactions were evaluated with the aid of data from the literature and the authors measurements of the concentration dependence of the surface tension and molar volume.