Application of phase diagram calculations to development of new ultra-high temperature structural materials

In-situ refractory metal intermetallic composites(RMICs) based either on (Nb, Si) or (Mo, Si, B) are candidate materials for ultra-high temperature applications (>1400 ℃). To provide a balance of mechanical and environmental properties, Nb-Si composites are typically alloyed with Ti and Cr, and Mo-Si-B composites are alloyed with Ti. Phase diagrams of Nb-Cr-Ti-Si and Mo-Si-B-Ti, as prerequisite knowledge for advanced materials design and processing development, are critically needed. The phase diagrams in the metal-rich regions of multicomponent Nb-Cr-Ti-Si and Mo-Si-B-Ti were rapidly established using the Calphad (Calculation of phase diagram) approach coupled with key experiments. The calculated isotherms, isopleths, and solidification paths were validated by experimental work. The important heterogeneous multiphase equilibria in both quaternary systems identified will offer engineers the opportunity to develop materials with a balance of properties for high-temperature applications.

CONTACT MATERIALS FOR GaSb AND InSb: A PHASE DIAGRAM APPROACH

The development of well defined and thermally stable ohmic contacts for Ⅲ- Ⅴ semi-conductors like InSb and GaSb is still a challenging problem in semiconductor devicetechnology. As device processing usually includes the exposure to elevated tempera-tures, interface reactions often occur during metallization and further heat treatment.It is thus important to understand the respective phase equilibria of the involved el-ements. From the thermodynamic point of view, binary and ternary compounds inequilibrium with the respective compound semiconductor would be the best choice forcontact materials as these contacts will be stable even after long exposure to elevatedtemperatures. These possible candidates for contact materials may be directly obtainedfrom the phase diagrams.During the last years we investigated several phase diagrams of transition metals withGaSb and InSb. Experimental results in the systems Ga-Ni-Sb, Ga-Pd-Sb, Ga-Pt-Sb,In-Ni-Sb and In-Pd-Sb are summarized and are discussed in the context of contactchemistry.

Individualized Pixel Synthesis and Characterization of Combinatorial Materials Chips

Conventionally, an experimentally determined phase diagram requires studies of phase formation at a range of temperatures for each composition, which takes years of effort from multiple research groups. Combinatorial materials chip technology, featuring high-throughput synthesis and characterization, is able to determine the phase diagram of an entire composition spread of a binary or ternary system at a single temperature on one materials library, which, though significantly increasing efficiency, still requires many libraries processed at a series of temperatures in order to complete a phase diagram. In this paper, we propose a "one-chip method" to construct a complete phase diagram by individually synthesizing each pixel step by step with a progressive pulse of energy to heat at different temperatures while monitoring the phase evolution on the pixel in situ in real time. Repeating this process pixel by pixel throughout the whole chip allows the entire binary or ternary phase diagram to be mapped on one chip in a single experiment. The feasibility of this methodology is demonstrated in a study of a Ge-Sb-Te ternary alloy system, on which the amorphouscrystalline phase boundary is determined.

Oxidation Kinetics of Aluminum Powders in a Gas Fluidized Bed Reactor in the Potential Application of Surge Arresting Materials

In this technical paper, the oxidation mechanism and kinetics of aluminum powders are discussed in great details. The potential applications of spherical aluminum powders after oxidation to be part of the surging arresting materials are discussed. Theoretical calculations of oxidation of spherical aluminum powders in a typical gas fluidization bed are demonstrated. Computer software written by the author is used to carry out the basic calculations of important parameters of a gas fluidization bed at different temperatures. A mathematical model of the dynamic system in a gas fluidization bed is developed and the analytical solution is obtained. The mathematical model can be used to estimate aluminum oxide thickness at a defined temperature. The mathematical model created in this study is evaluated and confirmed consistently with the experimental results on a gas fluidization bed. Detail technical discussion of the oxidation mechanism of aluminum is carried out. The mathematical deviations of the mathematical modeling have demonstrated in great details. This mathematical model developed in this study and validated with experimental results can bring a great value for the quantitative analysis of a gas fluidization bed in general from a theoretical point of view. It can be applied for the oxidation not only for aluminum spherical powders, but also for other spherical metal powders. The mathematical model developed can further enhance the applications of gas fluidization technology. In addition to the development of mathematical modeling of a gas fluidization bed reactor, the formation of oxide film through diffusion on both planar and spherical aluminum surfaces is analyzed through a thorough mathematical deviation using diffusion theory and Laplace transformation. The dominant defects and their impact to oxidation of aluminum are also discussed in detail. The well-controlled oxidation film on spherical metal powders such as aluminum and other metal spherical powders can potentially become an important part of switch devices of surge arresting materials, in general.

Design of the rare-earth-containing materials based on the micro-alloying phase equilibria, phase diagrams and phase transformations

Rare-earth(RE)elements,known as“industrial vitamins”,have permeated modern lives,especially in high-tech applications.Although the RE elements possess close chemical similarities and have been treated as“one element”in the periodic table,their characteristics differ from each other.The RE microalloying effect is the crux to ameliorate the physicomechanical and thermochemical properties of materials,thereby the study of RE-related phase diagrams becomes indispensable to the design and optimization of RE-containing materials.However,in reality,the knowledge base in this area is considerably scarce compared with that of other commonly-used elements.In this work,the phase equilibria,phase diagrams,phase transformations,and some recent examples of RE-containing materials design are summarized,with which one can predict the RE solubilities,the RE precipitates,as well as the corresponding service behaviors.The attainment of enhanced materials’properties suggests that the thermodynamic rules extracted from the phase diagrams could serve as fundamental criteria for the successful development of novel RE-containing materials.

Holographic alloy positioning design system and holographic network phase diagrams of Au-Cu system

Taking Au?Cu system as an example, three discoveries and two methods were presented. First, a new way for boosting sustainable progress of systematic metal materials science (SMMS) and alloy gene engineering (AGE) is to establish holographic alloy positioning design (HAPD) system, of which the base consists of measurement and calculation center, SMMS center, AGE center, HAPD information center and HAPD cybernation center; Second, the resonance activating-sychro alternating mechanism of atom movement may be divided into the located and oriented diffuse modes; Third, the equilibrium and subequilibrium holographic network phase diagrams are blueprints and operable platform for researchers to discover, design, manufacture and deploy advanced alloys, which are obtained respectively by the equilibrium lever numerical method and cross point numerical method of isothermal Gibbs energy curves. As clicking each network point, the holographic information of three structure levels for the designed alloy may be readily obtained: the phase constitution and fraction, phase arranging structure and properties of organization; the composition, alloy gene arranging structure and properties of each phase and the electronic structures and properties of alloy genes. It will create a new era for network designing advanced alloys.

Alloy gene Gibbs energy partition function and equilibrium holographic network phase diagrams of AuCu_3-type sublattice system

Taking AuCu3-type sublattice system as an example, three discoveries have been presented: First, the third barrier hindering the progress in metal materials science is that researchers have got used to recognizing experimental phenomena of alloy phase transitions during extremely slow variation in temperature by equilibrium thinking mode and then taking erroneous knowledge of experimental phenomena as selected information for establishing Gibbs energy function and so-called equilibrium phase diagram. Second, the equilibrium holographic network phase diagrams of AuCu3-type sublattice system may be used to describe systematic correlativity of the composition?temperature-dependent alloy gene arranging structures and complete thermodynamic properties, and to be a standard for studying experimental subequilibrium order-disorder transition. Third, the equilibrium transition of each alloy is a homogeneous single-phase rather than a heterogeneous two-phase, and there exists a single-phase boundary curve without two-phase region of the ordered and disordered phases; the composition and temperature of the top point on the phase-boundary curve are far away from the ones of the critical point of the AuCu3 compound.

Alloy gene Gibbs energy partition function and equilibrium holographic network phase diagrams of Au_3Cu-type sublattice system

Taking Au3Cu-type sublattice system as an example, three discoveries have been presented. First, the fourth barrier to hinder the progress of metal materials science is that today’s researchers do not understand that the Gibbs energy function of an alloy phase should be derived from Gibbs energy partition function constructed of alloy gene sequence and their Gibbs energy sequence. Second, the six rules for establishing alloy gene Gibbs energy partition function have been discovered, and it has been specially proved that the probabilities of structure units occupied at the Gibbs energy levels in the degeneracy factor for calculating configuration entropy should be degenerated as ones of component atoms occupied at the lattice points. Third, the main characteristics unexpected by today’s researchers are as follows. There exists a single-phase boundary curve without two-phase region coexisting by the ordered and disordered phases. The composition and temperature of the top point on the phase-boundary curve are far away from those of the critical point of the Au3Cu compound; At 0 K, the composition of the lowest point on the composition-dependent Gibbs energy curve is notably deviated from that of the Au3Cu compounds. The theoretical limit composition range of long range ordered Au3Cu-type alloys is determined by the first jumping order degree.

Rapid screening of magnetic properties in several Fe-X-Ni systems via combinatorial materials chip method

Fe-X-Ni(X=Cr,W and V)combinatorial thin-film(∼100 nm thick)materials chips covering the full composition range of ternary systems were fabricated.The crystal structure distribution was mapped by micro-beam X-ray diffractometers(XRD)and the magnetic hysteresis loops over the chip were characterized by a high-throughput magneto-optical Kerr effect(HT-MOKE)system to establish the composition-phase-magnetic properties relationships.The results showed that saturation magnetization for all systems has a strong dependency on alloying composition,and decreases with increasing dopped elements content as a general trend.Although the trend of saturation magnetization in bulk is in good agreement with that from thin films,all bulk samples show almost no coercivity,attributable to the much smaller grain size,and stronger texture in thin-film samples.Comparing the Fe-X-Ni systems under a similar condition,in the out-of-plane,Cr alloying obtained the largest coercivity(∼400 mT)followed by W alloying(∼300 mT)and then V alloying(∼200 mT).We suggest that alloying with different elements leads to the diverse orientation and crystallinity of the fcc phase resulting in different magnetic properties.Meanwhile,the effect of heat treatment on magnetic properties indicates that saturation magnetization is more closely related to the duration of heat treatment.

Optimization and Calculation of TbCl_3-ACl (A=Li, Na, K, Rb, Cs) Phase Diagrams

By using CALPHAD (Calculation of Phase Diagram) technique the optimization and calculation of the binary systems of TbCl_3-ACl (A= Li, Na, K, Rb, Cs) were carried out. For describing the Gibbs free energy of liquid phase in these systems the new modified quasichemical model in the pair-approximation for short-range ordering was used. From measured phase equilibria data and experimental integral properties the TbCl_3-ACl phase diagrams were optimized and calculated. A set of thermodynamic functions was optimized based on an interactive computer-assisted analysis. The calculated phase diagrams and thermodynamic data are self-consistent.

Development of a computational tool for materials design

An integrated modeling tool coupling thermo- dynamic calculation and kinetic simulation of multicom- ponent alloys is developed under the framework of integrated computational materials engineering. On the basis of PandatTM software for multicomponent phase diagram calculation, the new tool is designed in an inte- grated workspace and is targeted to understand the com- position-processing-structure-property relationships of multicomponent systems. In particular, the phase diagram calculation module is used to understand the phase stability under the given conditions. The calculated phase equilib- rium information, such as phase composition and chemical driving force, provides input for the kinetic simulation. In this paper, the design of the modeling tool will be pre- sented and the calculation examples from the different modules will also be demonstrated.

Liquid metal material genome： Initiation of a new research track towards discovery of advanced energy materials

As the basis of modern industry, the roles materials play are becoming increasingly vital in this day and age. With many superior physical properties over conventional fluids, the low melting point liquid metal material, especially room-temperature liquid metal, is recently found to be uniquely useful in a wide variety of emerging areas from energy, electronics to medical sciences. However, with the coming enormous utilization of such materials, serious issues also arise which urgently need to be addressed. A biggest concern to impede the large scale application of room-temperature liquid metal technologies is that there is currently a strong shortage of the materials and species available to meet the tough requirements such as cost, melting point, electrical and thermal conductivity, etc. Inspired by the Material Genome Initiative as issued in 2011 by the United States of America, a more specific and focused project initiative was proposed in this paper--the liquid metal material genome aimed to discover advanced new functional alloys with low melting point so as to fulfill various increasing needs. The basic schemes and road map for this new research program, which is expected to have a worldwide significance, were outlined. The theoretical strategies and experimental methods in the research and development of liquid metal material genome were introduced. Particularly, the calculation of phase diagram （CALPHAD） approach as a highly effective way for material design was discussed. Further, the first-principles （FP） calculation was suggested to combine with the statistical thermo- dynamics to calculate the thermodynamic functions so as to enrich the CALPHAD database of liquid metals. When the experimental data are too scarce to perform a regular treatment, the combination of FP calculation, cluster variation method （CVM） or molecular dynamics （MD）, and CALPHAD, referred to as the mixed FP-CVM- CALPHAD method can be a promising way to solve the problem. Except for the theoretical strategies, several parallel processing experimental methods were also analyzed, which can help improve the efficiency of finding new liquid metal materials and reducing the cost. The liquid metal material genome proposal as initiated in this paper will accelerate the process of finding and utilization of new functional materials.

Primary study of the isothermal phase diagram of the Cu_2O-Al_2O_3-SiO_2 ternary system at 1150℃ in air

The isothermal phase diagram of the Cu2O-Al2O3-SiO2 ternary system at 1150℃ was reported for the samples which were prepared from sol-gel method and quenched by water after being heated at 1150℃ for 12 h. Based on the conventional X-ray powder diffraction （XRD） and in situ high-temperature XRD quantitative analysis,in addition to scanning electron microscopy measurement,the phase identification was achieved. Combining the deduction from the component phase diagrams of the binary systems using the phase equilibrium theorem,the primary isothermal phase diagram was plotted over the composition area Cu2O-mullite-SiO2. In this area,the approximate composition areas of two two-phase regions and one three-phase region,（L2＋Cr）,（L2＋M）,and （L1＋L2＋Tr）,were determined. Moreover,the precise composition areas of both of the three-phase regions （L2＋Cr＋M） and （L2＋M＋A） were determined according to the results of conventional and in situ high-temperature XRD quantitative analysis by Rietveld method.

Voronoi-RBSM耦合的混凝土细观建模方法研究

为解决已有混凝土细观数值模拟方法计算效率低、对象尺寸受限的问题,提出一种基于Voronoi网格拓扑和刚体弹簧模型(RBSM)的混凝土细观建模新思路。该模型将混凝土视为由骨料、水泥砂浆组成的二相材料,骨料通过Voronoi单胞描述,视为刚性体,水泥砂浆简化为Voronoi单胞交界面的均布弹簧,弹簧刚度依据局部砂浆的实际情况自动定义。无需对骨料和水泥砂浆进行网格细化,可大大减少单元数量,允许Voronoi单胞在界面处侵入和分离,描述混凝土的变形、开裂等。为验证该文模型的有效性和适用性,开展了室内试验与数值模拟的对比研究,并分析了骨料占比等参数的敏感性。结果表明:基于Voronoi-RBSM的混凝土细观模型,可以较为高效、准确预测混凝土构件在加载过程中细观力学响应,对于尺寸较小的混凝土试件、尺寸较大钢筋混凝土简支梁均有较好的细观模拟效果,尤其是当网格尺寸与骨料平均粒径接近时,预测结果与试验结果最为接近。此外,模型的预测精度受骨料体积占比影响,骨料体积占比越小精度越低,因此,并不适用于浆体占比高的混凝土材料细观数值模拟。

WC-Ni基硬质合金的基础研究进展

WC-Ni基硬质合金可应用在磁性材料成形模具和核主泵机械密封关键部件等极端工况领域。由于材料体系的本征特性,WC-Ni基硬质合金的高性能化和质量稳定性控制一直面临挑战。两相区碳窗口、固液转变温度、液相烧结过程中的润湿行为,以及合金组元在黏结相中的固溶特性,是硬质复合材料成分及其制备工艺设计的关键参数。本文以制备工艺体系最完善的WC-Co基硬质合金为参比对象,从上述4个方面对WC-Ni基硬质合金的本征特性及其研究进展进行综述,旨在强化对WC-Ni基硬质合金本征特性的理解,为高性能WC-Ni基硬质合金新材料高效开发提供参考。

不同产地与不同生产方式的丹参药材质量相似性评价研究

本研究旨在明确不同产地、不同生产方式丹参药材的质量相似性,建立丹参药材主成分特征图谱以及色差指纹图谱,形成快速、科学的立体质量评价方法,并为丹参临床使用及不同地域药材生产提供数据参考。运用HPLC建立丹参药材指纹特征图谱质量分析方法,通过中药指纹图谱相似度评价系统和ModuleLab Chroman软件对丹参药材质量进行相似性评价及计量分析;采用主成分分析(PCA)、K最近邻法(KNN)等算法及可视化方法对样品丹参药材的色度值总体分布情况进行分析。结果显示,不同产地丹参药材共有11个共有峰,合成特征图谱相似度范围为0.894~0.999,表明不同产地样品化学成分差异较小,各产地丹参药材具有较好的相似度,但根据成分PCA得分载荷图与聚类分析显示,主成分贡献率为85.93%,其中丹酚酸B成分有较高的贡献率,说明丹酚酸B是造成不同产地差异的主要物质;主成分测定显示不同产地与不同生产方式的丹参药材总丹参酮类成分也具有较大差异,总丹参酮含量为1.358~7.515 mg/g,丹酚酸B含量为4.574~112.670 mg/g;药材颜色差异分析结果表明,不同产区丹参药材颜色具有显著差异,特别是广西地区丹参药材颜色差异更加明显,模型识别率达到93.75%。本试验评价方法能快速分辨丹参药材质量差异性,可为进一步进行临床疗效评价提供数据参考,为丹参药材生产方式以及临床应用提供思路。

敦煌写本S.5648《圆形方形诗图》创作时间考论

S.5648杂诗抄写本为册子本装帧形式,杂抄佛道相关文学作品。通过诗文词句对仗对此件所抄《圆形方形诗图》进行内容破读;运用写本学考证方法,考察S.5648写本同抄内容之间的内在关系,以及“霜”字等白色事物在金山国时期文学作品中的代表性,由此推测《圆形方形诗图》的创作时间为金山国时期,其性质为带有现实意义的杂体诗作品,抄写在此卷中的时间断为癸酉年913年。通过对P.3351《十字图诗》的实际用途和抄写情境的简要判断,系联S.5648写本,推断《圆形方形诗图》的抄写者为佛寺学郎,其用途一为情感抒发,二为日常娱乐。

基于标签属性的物质扩散推荐算法

针对推荐系统中数据稀疏问题,利用用户与产品之间的标签信息,提出了一种基于标签属性的物质扩散推荐算法。通过构建用户—产品标签和产品—用户标签二部图网络,分别计算产品对用户标签属性和用户对不同类型产品的推荐偏好特征向量,据此改进物质扩散算法中的资源分配方式。在MovieLens电影评分数据集上的对比实验结果表明,该算法在精准率、召回率、F1系数和多样性上都有一定程度的提高。

燕几图儿童纸家具设计探析

随着国民经济的发展和国民素质的逐步提高,社会对儿童家具的需求也不断提高。除了满足日常使用外,儿童家具应具备互动性、娱乐性、教育性、环保性、成长性等作用,以改变儿童使用家具的行为习惯和主动性为出发点,激发儿童的创造性和想象力。通过对燕几图的深入研究,古典造物艺术的典型代表,创造出美观舒适、功能实用为理念下的儿童家具设计,运用了《燕几图》中的模数化设计和矩阵设计思想,将其融入儿童纸质家具设计研究中。燕几图的形制与纸质材料结合,设计出一套适合儿童使用的组合家具。将中国传统家具的造物思想与现代设计相结合,使儿童家具更加具有实用性与趣味性。

轮胎材料分布图CAD参数化软件开发

基于C#编程语言,使用Winform进行图形界面开发,利用轻量化的MySQL数据库进行数据存储,基于CAD.NET API处理图形的参数化生成,开发一个轮胎材料分布图CAD参数化二次开发软件,以利于更快速、准确地进行材料分布图设计,并将结果导出为CAD图纸文件。该软件具有数据管理模块、CAD参数化模块和数据流转模块等功能模块,可以在Windows系统中运行,可提供友好的图形界面,与常见的CAD软件界面相似,支持用户进行可视化的操作和交互。