Computational thermodynamics,computational kinetics,and materials design

Computational thermodynamics, known as CALPHAD method when dawned in 1950s, aimed at cou- pling phase diagrams with thermochemistry by computa- tional techniques. It eventually evolves toward kinetic simulations integrated with thermodynamic calculations, i.e., computational kinetics, including diffusion-controlled phase transformation, precipitation simulation, and phase- field simulation. In the meantime, thermodynamic, mobility, and physical property databases for multi-component and multi-phase materials, served as basic knowledge for materials design, are critically evaluated by CALPHAD approach combining key experiments, first-principles cal- culations, statistic methods, and empirical theories. The combination of these computational techniques with their conjugated databases makes it possible to simulate phase transformations and predict the microstructure evolution in real materials in a foreseeable future. Further links to micro- and macro-scale simulations lead to a multi-scale compu- tational framework, and aid the search for the quantitative relations among chemistry, process, microstructures, and materials properties in order to accelerate materials devel- opment and deployment. This is a new route of materials and process design pursued by Integrated Computational Materials Engineering （ICME） and Materials Genome Ini- tiative （MGI）. This article presents a review on the basic theories and applications, the state of the art and perspective of computational thermodynamics and kinetics.     

Development and application of phase diagrams for Li-ion batteries using CALPHAD approach

Phase diagrams provide fundamental knowledge about design map of new electrode materials for Li-ion batteries. The CALPHAD (CALculation of PHAse Diagrams) approach is widely applied to the development of phase diagrams and property diagrams in a thermodynamic language. Within the CALPHAD framework, the theoretical modeling can be performed to predict phase equilibria, thermodynamics, electrochemical and physical properties of electrodes. This review provides the successful application of high quality calculated phase diagrams and thermodynamic property diagrams in CALPHAD investigation to both cathodes and anodes of Li-ion batteries, including Li–Co–O, Li–Ni–O, Li–Co–Ni–O, Li–Mn–O, Li–Cu–O, Li–Si, Li–Sb and Li–Sn systems with. The intensive CALPHAD-type research may also predict electrochemical properties, cell performance of the Li-ion batteries to achieve more efficient development of electrode materials.     

The materials genome and CALPHAD

The mapping of the human genome is an important basis for the development of new medicals and medical treatments.Consequently,it has attracted tremendous research funding over the last decade.On June2011,the Materials Genome Initiative was announced by the US President Obama as collaboration on modeling and advanced materials databases.Unfortunately,the materials genome was given a rather vague definition in the announcement.However,the materials genome should be defined in analogy with biological genomes and one may then conclude that:at any moment,the performance of a specific material depends on its chemical composition(inherent property stored in its genome)and its environment(external interactions–processing–conditions during usage).The materials genome should thus be defined as a set of information encoded in the language of thermodynamics obtained by careful assessment of experimental data and quantum mechanical calculations from which certain conclusions about the material can be drawn.The CALPHAD databases contain the thermodynamic and kinetic properties of a materials system.Such databases allow the prediction of materials structure as well as its response to processing and usage conditions,and are major parts of integrated computational materials engineering.     

相图计算及其在无铅焊接材料中的应用

随着Sn-Pb焊接材料在电子工业中的应用限制,无铅焊接材料的设计与开发已经是电子封装领域的重要课题.相图计算方法(CALPHAD)作为一种科学研究方法也越来越多的应用到材料的设计开发和工艺研究方面.相图计算主要是依据实验数据,建立热力学模型,根据Gibbs自由能最小原理计算相平衡.主要介绍了相图计算原理,以及根据已经评估的热力学数据,相图计算方法在无铅焊接材料的设计开发、焊接过程的界面反应、焊接凝固模拟等方面的应用.     

利用激光超声声谱技术研究凝聚态物质

利用脉冲激光在凝聚态物质中激发起声,并利用光干涉仪或压电换能器接收脉冲超声信号,即激光超声声谱技术,已广泛用于研究凝聚态物质的弹性性质和结构检测。近来特别发展了利用激光超声技术定征固体材料的热学特性,同时发展用于研究具有生物活性的物质的光解反应动力学和热力学过程,获得了非常满意的结果。     

横截面为三角形的半导体量子线结构的弹性解

在半导体异质微纳米结构中,晶格失配和热失配等因素引起的弹性场对结构的光学和电学等物理性能产生重要影响.研究了晶格失配和热失配在半导体量子线结构中所产生的弹性场,在分析圆柱形量子线结构弹性场的基础上,推导得到了任意截面形状量子线结构解的一般形式,并给出无限大基体内横截面为三角形量子线结构的解析结果.该结果可为进一步研究弹性场对半导体量子线结构物理性能的耦合作用打下必要的基础.     

High-throughput experimental tools for the materials genome initiative

The materials innovation infrastructure in the materials genome initiative(MGI)consists of three major components:computational tools,experimental tools,and digital data.This article will review experimental tools for high-throughput,high spatial resolution measurements of several materials properties such as elastic modulus,thermal conductivity,specific heat capacity,and thermal expansion.Application of these tools on compositionvarying samples such as diffusion multiples can be used to quickly and efficiently obtain composition–phase–structure–property relationships for materials property database establishment.They can also be used in conjunction with theoretical modeling to find and explain unusual effects to improve the predictability of models.More micron scale resolution experimental tools are in development.These high-throughput tools will be an essential part of MGI.     

Effective elastic moduli and interface effects of nanocrystalline materials

Many properties of nanocrystalline materials are associated with interface effects. Based on their microstructural features, the influence of interfaces on the effective elastic property of nanocrystalline materials is investigated. First, the Mori-Tanaka method is employed to determine the overall effective elastic moduli by considering a nanocrystalline material as a binary composite solid consisting of a crystal or inclusion phase with regular lattice connected by an amorphous-like interface or matrix phase. The effects of strain gradients are then examined on the effective elastic property by using the strain gradient theory to analyze a representative unit cell. Two interface mechanisms are elucidated that influence the effective stiffness and other mechanical properties of materials. One is the softening effect due to the distorted atomic structures and the increased atomic spacings in interface regions, and the other is the baffling effect due to the existence of boundary layers near interfaces.     

黑龙江省穆棱沸石矿物化性能的基本特征及评价

黑龙江省穆棱沸石矿的储量大、品位高、沸石类型好、物化性能优良。通过对穆棱沸石矿的热脱水失重值、阳离子交换性能、热稳定性能、耐酸性能、吸附性能、比表面积、比辐射率、化学成分及微量元素组成特征等物化性能的系统对比研究 ,评价了穆棱沸石矿在相关应用领域中的优势 ,为综合开发利用提供了重要的基础资料。     

新稀土金属间化合物晶体结构及高温晶格热膨胀性能研究

[目的]研究稀土-过渡族金属合金体系中的新稀土金属间化合物,挖掘稀土合金与化合物的新应用。[方法]利用扫描电子显微镜和能谱仪分析合金样品及其组成物相的成分,采用X射线粉末衍射技术研究和测定新金属间化合物的晶体结构及高温晶格热膨胀性能,并对所研究的新金属间化合物的高温热膨胀性能进行总结分析。[结果]不同的合金元素可以形成结构类型相同的晶体结构,得到了部分新金属间化合物的晶格热膨胀系数,这些新稀土金属间化合物的平均晶格热膨胀系数在10~(-6)到10~(-5)数量级之间,它们的平均单胞体积热膨胀系数也在同一数量级。[结论]化学性质相近的合金元素可以相互替代形成同构型金属间化合物。利用X射线粉末衍射同构法可测定新化合物的晶体结构,该法适用于解析二元、三元乃至多元新化合物的晶体结构。所研究的新稀土金属间化合物的热膨胀系数分别满足其各自所属晶系的热膨胀关系。     

Perspective on Materials Genome~

The author’s perspective on Materials Genome is presented in this paper through several related projects.Current thermodynamic and kinetic databases of multicomponent materials consist of Gibbs energy functions and atomic mobility of individual phases as functions of temperature,composition,and sometimes pressure,i.e.,with the individual phases based on crystal structures as the genome(building blocks)of materials.It is articulated that if an individual phase has its internal configurations,such as magnetic spin configurations and ferroelectric polarization,change significantly with respect to temperature,stress,and magnetic and electric fields,then those individual configurations instead should be considered as the genome of the individual phase.The‘‘mutation’’of an individual phase is governed by the entropy of mixing among the individual stable and metastable configurations,named as microstate configurational entropy,and responsible to anomalies in individual phases.Our ability to tailor the properties of those individual configurations as a function of compositions is the key for the design of materials.     

MgH2的结构与热力学性质的第一性原理研究

采用基于密度泛函的第一性原理方法计算了四角形MgH2的电子结构,通过准谐德拜模型研究了MgH2在压强为0～100 GPa,温度为0～600 K范围内的热力学性质。研究得到了MgH2零温零压下的平衡体积V、晶格常数、带隙,以及体弹模量B0、摩尔定压热容Cp,m、熵S、德拜温度Θ、体膨胀系数α随温度和压强的变化关系。     

MgH_2的结构与热力学性质的第一性原理研究

采用基于密度泛函的第一性原理方法计算了四角形MgH2的电子结构,通过准谐德拜模型研究了MgH2在压强为0～100 GPa,温度为0～600 K范围内的热力学性质。研究得到了MgH2零温零压下的平衡体积V、晶格常数、带隙,以及体弹模量B0、摩尔定压热容Cp,m、熵S、德拜温度Θ、体膨胀系数α随温度和压强的变化关系。     

Experimental investigation and thermodynamic assessment of the yttriumhydrogen binary system

A coupled experimental investigation and thermodynamic study of the yttrium-hydrogen(Y-H) binary system were carried out to provide more comprehensive and quantitative insights into the key thermodynamic properties of this system. Y-H system in the full range of H/Y = 0–3.0 was investigated by accurate pressure composition isotherm(PCI) measurement to provide credible phase equilibria information and thermodynamic data.The phase boundaries obtained were in agreement with previous experimental data but with improved accuracy.With the guide of the crystal structures, all the solid phases were modelled using the three sublattice model. The Y-H phase diagram and thermodynamic parameters were calculated and assessed with the CALPHAD technique.The obtained results are in very good agreement with our experimental data and the published data reported in literature. The obtained thermodynamic database of Y-H system can be used to predict the hydrogenation behavior and decomposition temperatures of hydrides.     

Development of thermodynamic and kinetic databases in micro-soldering alloy systems and their applications

Recent progress in the development of thermodynamic and kinetic databases of micro-soldering alloys,which were constructed within the framework of the Thermo-Calc and DICTRA software,was presented.Especially,a thermodynamic tool, ADAMIS(alloy database for micro-solders) was developed by combining the thermodynamic databases of micro-solders with Pandat,a multi-component phase diagram calculation software program.ADAMIS contains 11 elements,namely,Ag,Al,Au,Bi,Cu, In,Ni,Sb,Sn,Zn and Pb,and can handle all c...     

凝析油气体系流固耦合相平衡计算新方法

在分析了孔隙介质内表面吸附、毛细凝聚、毛细管压力等界面物理化学效应和应力变形对孔隙介质中流体相态影响的现象学特征和影响机制的基础上,通过在大尺度空间常规流体相平衡热力学模型中引入界面物理化学效应的影响,同时通过高才尼卡尔曼方程将毛细管半径与孔隙介质储渗特性的应力敏感性研究成果相关联,建立了同时考虑储层应力变形和界面物理化学效应影响的微孔隙尺度条件下的低渗特低渗凝析气藏多相流体流固耦合露点压力、pT相图及定容衰竭相平衡热力学计算模型。该模型的初步应用表明,其相态模拟计算结果能更为合理地解释孔隙介质环境中的凝析油气体系相态特征实验研究结果。     

地球内核物态热效应研究

 在考虑Grüneisen系数、Debye温度随体积变化的基础上,详细讨论了各部分热压的贡献,并且结合K-primed冷压方程,得到了地球内核较为全面的物态方程,分析了内核p-V-T的关系,给出了地球内核的温度分布.其结果详实有据,为以后深入研究地球内核甚至液态外核的物态性质提供了坚实的基础.     

EuCl3-CaCl2二元系的热力学优化和计算

引入短程有序-扩展似化学模型来描述EuCl3-CaCl2二元体系液相的Gibbs自由能,根据实验测定的相图和混合焓数据,运用CALPHAD技术对该体系进行了热力学优化和计算,优化计算的结果和实测值符合很好.     

Simulation of mesoscale interfacial properties using the lattice Boltzmann method

We derive the mesoscopic interparticle potentials from macroscopic thermodynamics for van der Waals, Redlich-Kwong, and Redlich-Kwong-Soave equations of state and find that all these potentials are very similar to the Lennard-Jones potential. To in-vestigate the interfacial property at the mesoscale level, we incorporate free energy functions into the single-component multiphase lattice Boltzmann model and obtain the saturated density coexistence curves and interface mass density profiles across the interface using this method with different equations of state. The simulation results accurately reproduce the properties of equilibrium thermodynamics. Numerical results for single-component phase transitions indicate that a bubble-growth process is obtained and the equilibrium phase diagram is achieved at a given temperature. Bulk free energy, the interfacial energy coefficient, and other properties of nonequilibrium thermodynamic parameters, which are used to examine interfacial properties, are obtained in these simulations, and all these parameters are found to obey irreversible thermodynamics.     

泡沫铝:新型超轻多孔金属的制备方法与性能

泡沫铝是一种新型超轻多孔金属,具有超轻、高比强、高比刚、阻尼减振、高冲击能量吸收和优异的热、电、磁性物理和应用性能,实现了结构材料的多功能化,因而展现了广阔的应用前景。泡沫铝可以通过采用熔体发泡法、渗流法、熔模铸造和电镀法、粉末冶金法和吹气法等制备,相应的方法所制备出的泡沫铝具有各自的孔结构,因而可以针对于满足相应的高技术应用需求。