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.     

含Er高Nb-TiAl基合金的热力学性能

基于Miedema混合焓模型外推出三元合金的热力学性能,利用合金成分的特点计算出了Ti-46Al-8Nb-0.1Er四元合金的各组元间的部分热力学性能,并结合Toop模型得出合金的组元活度及活度系数。结果表明,在此四元系中Er只与Al发生反应,与其它组元之间无反应,生成Er-Al化合物。然而在热力学上,Er2O3比Er-Al化合物更易形成,实验中熔体里不可避免的微量氧的介入,使得合金熔炼过程中Er首先与O结合形成Er2O3颗粒,且此Er2O3相在XRD测试分析证明得到。Er具有净化合金熔体、降低合金基体氧含量和析出强化的作用。     

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。     

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.     

Al-Cu-RE三元合金热力学性质的Miedema理论计算

合金形成焓是确定合金的稳定性及其非晶形成能力的重要因素。采用Miedema理论和几何外推模型相结合,预测了Al-Cu-RE(RE=La~Lu)体系液态合金整个成分范围的混合焓。计算结果表明:Al-Cu-RE三元体系的混合焓比Al-Cu二元合金的混合焓更负,稀土元素与Al、Cu之间的化学势差对混合焓的贡献起主要作用。当铝与稀土元素含量相同时,随着铜含量的减少,合金混合焓越来越负,从而表明在Al-Cu合金中加入稀土元素有利于Al-Cu-RE三元合金的形成。同时较负的混合焓是合金体系易于非晶化的重要条件之一,也说明Al-Cu-RE三元体系非晶形成能力较强。计算了Al8Cu4RE和Al Cu RE等三元化合物的形成焓,计算得到的Al Cu RE的形成焓比相应的Al8Cu4RE的形成焓要负,说明Al Cu RE更稳定;同时计算了金属间化合物Al(Cu1-xREx)3、Al(Cu1-xREx)、Al2(Cu1-xREx)的形成焓随稀土含量变化趋势。计算结果为Al-Cu-RE体系非晶形成的成分设计和相关性能研究提供了重要的热力学数据。     

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。     

新型FeMB系纳米晶软磁材料的成分设计

运用Miedema理论,系统计算Fe,B与Cu,Mo,Ni,Cr,V,Ga,Nb,Hf和Zr等元素形成合金系时的热力学性质。运用理想溶液理论,计算1 600 K时该二元合金系的过剩Gibbs自由能、过剩熵和活度。结果表明,在FeMB体系中,Fe-Zr-B的混合焓最小;1 600 K时Fe-M-B体系的过剩Gibbs自由能与其混合焓相似,其过剩熵趋近于零,活度相对于理想溶液偏差极小,在实际应用中可忽略不计。     

Mg-Sc合金组元活度及其相互作用系数计算

组元活度的获得是合金热力学性质研究的一个重要方面。由于高温实验的复杂性和精确度的不确定性,通过实验直接测定合金组元的活度受到了很大限制。运用合金的热力学性质,通过计算得到合金组元的活度是近年来合金热力学研究的一个热点。在各种预测合金热力学性质的模型中,Miedema模型是近年来发展得较为完善和准确的模型。本文则根据Miedema合金生成焓模型,计算了Mg-Sc合金液态和固态时的生成焓。结合相关的热力学关系式,计算了该合金中Sc的活度曲线,并拟合计算了该合金的相互作用系数,发现本文所采用的Miedema模型和正规溶体模型对于Mg-Sc合金是适用的。     

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。     

稀土系贮氢合金的生成焓计算

利用Miedema理论和几何模型计算了二元合金系La M ,Ni M和三元合金系LaNi5-xMx(M =Co ,Mn ,Al,Cr ,Fe,Cu)的生成焓。对二元合金系 ,计算结果与已有实验结果在xM ≥ 70 % (摩尔分数 )范围符合得较好 ;三元合金系计算结果表明 ,当分别添加合金组元Mn ,Co ,Cr,Fe和Cu时 ,LaNi5-xMx 的生成焓不同程度地增大 ,其中Cr ,Fe和Mn的影响较大 ,而添加Al时生成焓明显减小。讨论了生成焓对合金高温氢化时发生歧化反应的影响 ,合金的生成焓越大 ,越有利于歧化反应。     

医用Ti基合金形成焓的改进Miedema模型计算

采用改进Miedema模型计算医用Ti基合金的形成焓.结果表明,在医用Ti基合金中掺入非过渡金属A1或Sn能显著降低医用Ti合金的形成焓.对于Ti-Zr系合金形成焓,弹性形成焓的贡献较化学形成焓贡献大.     

Enthalpies of formation of compounds in Al-Ni-Y system

The enthalpies of formation of the ternary compounds Al4NiY, Al2NiY, Al2Ni6Y3, Al16 Ni3Y, AlNiY, Al3Ni2Y, AlNi8Y3, Al7Ni3Y2, and of the binary comp ounds Al2Y containing nickel and Ni5Y containing aluminum have been determined by high temperature reaction calorimetry. The enthalpy values measured are compared to previously published results where available as well as extended Miedema model predictions. The melting points of the compounds were determined by DTA and X-ray diffraction was used to confirm the crystal structures of the compounds. The enthalpi es of formation of the ternary compounds show a maximum along the 50%Al (mole fr action) section. The ternary compounds appear along lines of constant yttrium content consistent with binary compound solubility extensions.     

Thermodynamic calculation of Er-X and Al-Er-X compounds existing in Al-Mg-Mn-Zr-Er alloy

Based on the Miedema model and Extended Miedema theory, the formation energies of different solute components in Er-X binary system and Al-Er-X ternary systems were calculated. The results show that the variation of erbium content has little influence on the chance rate of the formation Al-Er compound in the Al-Mg-Mn-Zr-Er system. The calculated formation energies in the Er-X binary system and Al-Er-X ternary systems indicate that Al3Er phase can take priority of depositing, Al-Er-Zr ternary compounds may also found which agrees with the experimental results in references. The consistency of calculation and experiment proves that the intermetallic compounds in the Al-Mg-Mn-Zr-Er system can be predicted directly by calculating the formation energies of the reactions in Er-X binary system and Al-Er-X ternary systems with the Miedema model and Extended Miedema theory.     

Al-Si-Fe三元合金各组元活度的计算

由ＡｌＳｉＦｅ 三元系的三个二元子系用Ｂｏｎｎｉｅｒ 法计算和讨论了ＡｌＳｉＦｅ 合金在不同温度下各组元的活度。结果表明， 该三元系中各组元活度均有负偏差， 尤以Ｆｅ 的偏差为大。当Ａｌ 含量较高时，合金中Ａｌ 的活性可近似于纯金属Ａｌ 的活性。三元系中Ａｌ 含量不变时， 增加Ｆｅ 的含量， 即用Ｆｅ 代替部分Ｓｉ 可使Ａｌ 的活度有所增加。对于ＡｌＳｉＦｅ 三元系的计算，Ｂｏｎｎｉｅｒ 法比其它解析计算方法简单     

Thermodynamic analysis of alloys Ti–Al, Ti–V, Al–V and Ti–Al–V

Thermodynamic analysis of three binary Ti-based alloys: Ti–Al, Ti–V, and Al–V, as well as ternary alloy Ti–Al–V, is shown in this paper. Thermodynamic analysis involved thermodynamic determination of activities, coefficient of activities, partial and integral values for enthalpies and Gibbs energies of mixing and excess energies at four different temperatures: 2000, 2073, 2200 and 2273 K, as well as calculated phase diagrams for the investigated binary and ternary systems. The FactSage is used for all thermodynamic calculations.     

Enthalpy of formation of quasicrystalline phase and ternary solid solutions in the Al-Fe-Cu system

1. Introduction A novel intermetallic-phase quasicrystal was discovered in 1984. At first, the quasicrystalline phase was observed in rapidly quenched alloys of the Al-Mn system [1]. Till date quasicrystalline phases have been obtained in more than 100 systems; mainly Al, Cu, Ti, and Zr-based systems. The pecu- liarity of the quasicrystalline phases is that the exis- tence of symmetry axes for the fifth and tenth orders are forbidden by classic crystallography. The quasi- crystalline phases…     

铝-稀土金属间化合物形成焓的计算

详细分析了二元铝-稀土金属间化合物的形成焓的Miedema计算值和文献报道数据的误差分布.结果表明,计算值相比于文献中实验数据普遍呈现负偏差.为此,计算研究中需要针对铝-稀土元素重要的影响因子--稀土原子与铝原子的半径比来修正热力学计算模型.对铝-稀土金属间化合物的系列计算结果及其误差分析说明,修正的Miedema模型计算值更加接近实验值,误差由原来的36%缩小到目前的5%.并利用MTDATA热力学计算软件部分验算计算结果,证明依据新模型的热力学计算预测更加准确可靠.用新模型计算了常见的铝-稀土金属间化合物的形成焓,同时也计算了Al-Er,Al-Tb,Al-Gd 等研究数据缺乏的铝-稀土金属间化合物的形成焓.     

PREDICTION OF THE MIXING ENTHALPIES OF BINARY LIQUID ALLOYS BY MOLECULAR INTERACTION VOLUME MODEL

The mixing enthalpies of 23 binary liquid alloys are calculated by molecular interaction volume model （MIVM）, which is a two-parameter model with the partial molar infinite dilute mixing enthalpies. The predicted values are in agreement with the experimental data and then indicate that the model is reliable and convenient.     

Ternary Au-Ga-Sb system: calculation of thermodynamic properties using general solution model

The calculated results of thermodynamic properties in ternary Au-Ga-Sb system by general solution model were presented in this paper.The calculations were carried out in nine cross sections from all three corners in the temperature range of 973–1,573 K,and integral molar excess Gibbs energies,partial molar Gibbs energies,activity coefficients and activities for all components are obtained.The activity of gold and gallium shows negative deviation from Rault's law for all investigated sections,while antimony activity is close to the line of ideal conditions and even coincides with the line for high content of antimony in the alloy.Data obtained by calculation were compared with those found in literature.It is concluded that compared values show reasonable good agreement.