A miniature dynamic magnetoelectric test method by shielding coil

磁电效应是施加磁场产生电极化的物理效应,动态法测量磁电转换系数,是测量磁电材料的磁电效应的一类主要方法。本文尝试设计了一种屏蔽线圈式的微型磁电测; 试方法,改变了以往的电磁屏蔽方式,从屏蔽样品改为屏蔽线圈,并采用单线圈的设计,从而扩大了样品空间,提供一种可以微型化,便于嵌入低温系统的动态法磁; 电效应测试方法。Magnetoelectric effect is the effect that applied magnetic field induces; an electric polarization. The dynamic method is the main test method of; magnetoelectric coefficient. Here, this article attempted to design a; miniature test system by shielding coil. In this design, shielding; method was changed from sample-shielding to coil-shielding and the coil; was changed from dual-coils to single-coil. After changing, the sample; space is enh anced obviously, while the test system size is very small.; This study provides a miniature dynamic magnetoelectric test method; which can be easily embedded into general cryogenic system

Reaction kinetics and phase diagram studies in the Ti-Zn system

Ti-Zn phase diagram and layers growth kinetics, have been studied at 500, 600 and 900degreesC. Linear growth has been observed. The calculated values of the growth constants K-G are: at 500degreesC, K-G = (7.5 +/- 0.3) x 10(-9) m s(-1); at 600 degreesC, K-G = (8.0 +/- 0.2) x 10(-9) m s(-1). An indication about the presence of a formerly unknown compound (Ti2Zn3) has been found out by electron microprobe analyses and optical microscopy. Homogeneity ranges (probably metastable) have been observed for some phases that are considered to be stoichiometric. (C) 2003 Elsevier B.V. All rights reserved

Materials Genome Initiative and Nuclear Fuel Element Material

核能由于其高能量密度和低污染排放等优点,已经成为未来能源的重要组成部分。然而,民用核燃料材料因其特殊的放射性,实验研究的安全防护成本极高,尤其是; 经过辐照后的核燃料材料,分析和表征手段极其有限,如果采用传统的试错法材料研发方法,将会使材料的研发成本大幅提高,因此,材料基因工程的研究思路正是; 适合于新型民用核燃料材料研究的技术路线。本研究组多年来以开发新型民用核燃料元件材料为目标,通过第一性原理和CALPHAD技术的结合,先后建立了U; 、Pu等锕系元素的多组元热力学数据库,并建立了辐照场作用下的热力学模型,对辐照场作用下核燃料材料的相变热力学和动力学进行了深入研究,在热力学数据; 库的基础上,运用相场动力学模型对核燃料元件材料的凝固和时效过程组织演化规律进行了系统的研究。这种基于材料基因工程的多尺度、多组元的材料设计研发思; 路为我国新一代具有自主知识产权的民用核燃料元件材料的成分设计、组织控制、工艺优化、性能改善及服役时间预测提供了重要的理论基础,同时对材料基因工程; 方法在材料开发中的广泛应用具有重要意义。Nuclear energy is an important part of the future source of energy due; to their higher energy density and lower emission of pollutants.; However, the traditional research method of "trial-and-error" may result; in higher costs and lower efficiency because of the radioactivity of the; nuclear fuel element material. The idea of Materials Genome; Initiative(MGI) is suitable for the research and development of the; nuclear fuel element material. Focused on the nuclear fuel element; material,our research group developed a multi-component thermodynamic; database including U,Pu and other elements,by coupling CALPHAD method; and the first-principle method. Based on the thermodynamic database, the; thermodynamic model under irradiation was established and the phase; transformations under irradiation were systematically investigated. The; microstructure evolutions during solidification and aging were simulated; by using the Phase-Field method. The present multiscale and; multi-component materials design method based on MGI can provide; important information for the design of composition,microstructure; controlling and property improvement of nuclear fuels materials.中央高校基本科研业务费; 国家自然科学基金资助项

Design of Pb-free solders in electronic packaging by computational thermodynamics and kinetics

Computational thermodynamics and kinetics were used to design the Pb-free micro-solders for replacing the conventional Sn-Pb solders because of the health and environmental safety problem. On the basis of CALPHAD (Calculation of Phase Diagrams) method we can easily calculate properties such as the liquidus projection, isothermal and vertical sectional diagrams and phase fraction in multi-component system including Ag, Bi, Cu, In, Sb, Sn, Zn and Pb elements. In addition, other related information such as the surface tension, viscosity of the liquid phase and solidification simulation can also be obtained. DICTRA (Diffusion Controlled Transformation) software was used to simulate the interfacial reactions between substrate and Pb-free solders, which can easily give the information on the growth of intermetallic compounds and moving speed of interface between substrate and solders etc

Calculation of phase diagrams in AlxIn1-xAs/InP, AsxSb1-xAl/InP and AlxIn1-xSb/InSb nano-film systems

通讯作者地址: Liu, XJ (通讯作者), Xiamen Univ, Dept Mat Sci & Engn, Coll Mat, Res Ctr Mat Design & Applicat, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Dept Mat Sci & Engn, Coll Mat, Res Ctr Mat Design & Applicat, Xiamen 361005, Peoples R China 电子邮件地址: [email protected] models for calculation of phase diagrams of semiconductor thin films with different substrates were proposed by considering the contributions of strain energy, the self-energy of misfit dislocations and surface energy to Gibbs free energy. The phase diagrams of the AlxIn1-xAs and AsxSb1-xAl thin films grown on the InP (1 0 0) substrate, and the AlxIn1-xSb thin films grown on the Insb (1 0 0) substrate at various thicknesses were calculated. The calculated results indicate that when the thickness of film is less than 1 mu m, the strain-induced zinc-blende phase appears, the region of this phase extends with decreasing of the layer thickness, and there is small effect of surface energies of liquid and solid phases on the phase diagrams. (C) 2009 Elsevier B.V. All rights reserved.National Natural Science Foundation of China 50425101 50571084 Ministry of Science and Technology 2009DFA5217

三元调幅分解型合金扩散偶中界面片层组织的相场模拟

采用相场动力学方法,研究了三元调幅分解型合金扩散偶中的浓度起伏、界面初始浓度差和组元原子迁移率对界面组织演化的影响.研究结果表明,由于扩散偶界面处浓度的突变引起化学势在扩散偶界面处的不连续变化,从而在扩散偶界面附近形成了两相交替排列的周期性片层组织,这种周期性片层组织的片层数随着初始浓度起伏的减小而增加.界面初始浓度差和组元原子迁移率对周期性片层组织的片层数影响较小,但对片层组织的形成时间和粗化过程影响较大.国家重点研发计划(2017YFB0702401);;中央高校基本科研业务费专项(20720170038,20720170048

Geometric analysis of the grand potential and a calculation procedure of phase equilibria by CVM

Based on the definition of grand potential, a geometric method for obtaining a grand potential-effective chemical potential diagram from the relevant molar free energy diagram was proposed, and the effect of magnetic transition on grand potential was also discussed. It is shown that the grand potential and effective chemical potential in a ferromagnetic state can be separated into paramagnetic and magnetic terms. In addition, a hybrid calculation procedure of phase equilibria with magnetic transition based on CVM, combined with the geometric analysis was proposed and is applied to the alpha/gamma phase equilibrium in the Fe-Mn binary system. It is shown that this method is feasible

纯钚在辐照条件下相稳定性的热力学研究

Pu(钚)是一种十分重要的核工业原料,随温度变化会有不同的结构,并且辐照对其有着重要的影响。为了探究辐照强度、辐照时间对钚的相变化的影响,本研究在纯Pu的吉布斯(Gibbs)自由能计算基础上,通过考虑辐照条件下空位产生的过剩自由能,建立了纯Pu在辐照条件下的热力学模型。计算不同辐照条件下的温度-吉布斯自由能函数,得到了不同辐照强度下纯Pu的相图,分析不同辐照强度、辐照时间对其6个同素异构体相稳定性的影响。研究结果表明:辐照对较低温度下纯Pu的相稳定性影响较大,接近室温时出现了γ-Pu的相区,其稳定存在的温度范围会随着辐照的强度增强、辐照时间加长而扩大,而且辐照使α-Pu趋于稳定。本研究所建立的辐照条件下的纯Pu的相图为Pu基核燃料的设计提供重要的基础理论指导。科技部重点研发计划(No.2017YFB0702401);;中央高校基本科研业务费专项资金(No.20720170038)资助~

Thermodynamic modeling of the Pb-U and Pb-Pu systems

通讯作者地址: Wang, CP (通讯作者), Xiamen Univ, Dept Mat Sci & Engn, Coll Mat, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Dept Mat Sci & Engn, Coll Mat, Xiamen 361005, Peoples R China 2. Xiamen Univ, Res Ctr Mat Design & Applicat, Xiamen 361005, Peoples R China 电子邮件地址: [email protected] thermodynamic assessments of the Pb-U and Pb-Pu binary systems were carried out using the CALPHAD (calculation of phase diagrams) method based on experimental data for thermodynamic properties and phase equilibria. The Gibbs free energies of the liquid, bcc, fcc, (alpha U), (beta U), (delta'Pu), (gamma Pu), (beta Pu) and (alpha Pu) phases were described by a subregular solution model with the Redlich-Kister equation, and those of the intermetallic compounds (Pb3U, PbU, PbPu3, Pb3Pu5, Pb4Pu5, Pb5Pu4, alpha Pb2Pu, beta Pb2Pu and Pb3Pu) by a two-sublattice model. The thermodynamic parameters for the two binary systems were optimized to consistently reproduce the available experimental data with satisfactory agreement. (C) 2010 Elsevier B.V. All rights reserved.National Natural Science Foundation of China 5077108

Influence of lanthanum ion-implantation on adhesive property of oxide film formed on Co-40Cr alloy

The isothermal and cyclic oxidizing kinetics of Co-40Cr alloy and its lanthanum ion-implanted samples were studied at 1 000 degrees C in air by thermal gravimetric analysis (TGA). Scanning electron microscopy (SEM) was used to examine the Cr2O3 oxide film's morphology after oxidation. Secondary ion mass spectrum (SIMS) method was used to examine the binding energy change of chromium caused by La-doping and its influence on the formation of Cr2O3 film. Acoustic emission (AE) method was used in situ to monitor the cracking and spalling of oxide films during oxidizing and subsequent air-cooling stages. Laser Raman spectrum was used to examine the stress changes within oxide films. A theoretical model was proposed relating to the film fracture process and was used to analyze the AE spectrum both on time domain and AE-event number domain. It was found that lanthanum implantation remarkably reduced the isothermal oxidizing rate of Co-40Cr and improved the anti-cracking and anti-spalling properties of Cr2O3 oxide film. The reasons for the improvement were mainly that the implanted lanthanum reduced the grain size and internal stress of Cr2O3 oxide, increased the high temperature plasticity of oxide film, and remarkably reduced the number and size of Cr2O3/Co-4OCr interfacial defects