电镀 Cu-W-Ni 合金的热力学分析

借助25℃下的Cu-H2O,Ni-H2O和W-H2O的E-pH图,说明了电镀Cu,W,Ni的可能性及范围,并重点分析了电镀Cu-W-Ni合金的可能性。Cu-Ni能在Cu-H2O与Ni-H2O系E-pH图叠合形成的共沉积区里析出。因Cu-H2O与W-H2O系的E-pH图叠合时无法形成Cu-W的共沉积区,Cu-W不能在其对应离子的水溶液中析出,但Ni-W能在Ni2+,WO42-水溶液里诱导共沉积。理论和实验证明,在含Cu2+,Ni2+,WO42-的水溶液中能电镀制备Cu-W-Ni合金。     

Thermodynamics of Selected Ti-Al and Ti-Al-Cr Alloys

Two alloys in the Ti-Al system (Ti-45 a/o Al,Ti-62Al) and three alloys in the Ti-Al-Cr system(Ti-47Al-2Cr, Ti-47Al-13Cr, Ti-51Al-12Cr) were selectedfor a thermodynamic study because of interest in their high-temperature oxidation behavior. Activitiesof Al and Ti were measured using a twin Knudsen-cellassembly with one cell acting as an internal standard.For the Ti-45Al alloy, Al activity was also measured with an EMF technique. The Ti-Al-Cr data wereconsistent with the Al and Ti activities expected fromthe adjacent binary Ti-Al phase fields. Implications ofthis work on oxidation properties arediscussed.     

Heusler合金Mn2TiGe的电子结构与磁性研究

基于密度泛函理论(DFT),采用第一性原理赝势方法,结合广义梯度近似(GGA),对Mn2TiGe Heusler合金的电子结构、磁性及半金属特性进行了研究.结果表明,Mn2TiGe的稳定晶体结构是Mn2CuAl型晶体结构;由能带计算得到Mn2TiGe的自旋磁矩为1.97 μB,其中Mn、Ti、Ge原子的自旋磁矩分别为0.71、-0.39、-0.03 μB.     

New Contribution to the Thermodynamics of Fe-Cr Alloys as Base for Ferritic Steels

High chromium ferritic-martensitic steels are commonly used for industrial applications requiring high strength at elevated temperature. Such steels typically contain 9-14 at.% Cr and a few percents of minor alloying elements. In recent studies it has been shown that the Cr solubility limit of the standard Fe-Cr phase diagram in that composition range is significantly underestimated. For the purpose of more reliable engineering and out of physical considerations, we reparameterize the Gibbs free energy so that the correct Cr solubility at low temperature (<700 K) is reproduced, while leaving the rest of the phase diagram changed only slightly. The mixing enthalpy and heat capacity resulting from the new parameterization are also compared with experiments and found to be in good agreement.     

NiTi合金的电子结构及缺陷作用的符合正电子湮没研究

利用双探头符合系统，测量了纯金属Si、Ni、Ti以及5种不同成分的NiTi合金的正电子湮没辐射Doppler展宽谱，计算了NiTi合金的形参数。结果表明，当Ni原子和Ti原子形成NiTi合金时，两原子中均有部分3d电子被局域化并形成共价键，导致合金基体中参与形成金属键的自由电子减少。在NiTi合金中金属键和共价键同时存在。成分为Ni-49at％Ti合金的W参数最高，表明该成分的合金中所含的缺陷数量最少，这可能是该成分合金形状记忆效应较好的原因。     

First-Principles Investigation on Electronic Structure and Optical Properties of Wurtzite InxGa1-xN Alloys

采用密度泛函理论框架下的第一性原理平面波超软赝势方法,研究In掺杂对纤锌矿InxGa1-xN合金的晶格常数、能带结构、态密度和光学性质的影响。计算结果表明：随着In掺杂浓度的增加,晶格常数逐渐增大,导带向低能方向移动,带隙变窄;与此同时,介电函数向低能方向发生了漂移,发生了红移现象。在2.0 eV附近出现了第一个介电峰,在4.76 eV附近出现了最大的介电峰。在大约5.6 eV和9.2 eV处有两个交叉点,当光子能量低于5.6或者高于9.2 eV,低掺杂浓度(小于50%)的吸收系数小于高掺杂浓度的吸收系数;当光子能量在5.6到9.2 eV之间,低掺杂浓度的吸收系数高于高掺杂浓度的吸收系数。研究结果表明InxGa1-xN合金可以作为太阳能电池以及透明导电薄膜的材料     

Understanding the Thermodynamics and Crystal Structure of Complex Fe Containing Intermetallic Phases Formed on Solidification of Aluminium Alloys

JOM - Ab initio density-functional theory calculations were carried out to investigate the energetics and structure of key Fe-containing intermetallic phases that precipitate from cast Al-Si...     

电子结构对La,Zr双掺杂γ-TiAl基合金延性的影响

γ-TiAl基合金具有优良的高温性能,且低密度、高比强度,在航空航天等领域备受青睐,室温延性差则制约着此类材料的广泛应用。以密度泛函平面波赝势方法为基础,计算研究了16个La和（或）Zr替代掺杂γ-TiAl体系（S1,S2,S3,S4,S51~S55,S61~S65,S7和S8）的结构与性质。对平均形成能的计算分析表明,它们均有较好的能量稳定性;根据弹性常量和Born-Huang判据预测,除S61外,15个掺杂体系均具有力学稳定性,预报它们是可以实际制备并稳定存在的。通过对比各体系的弹性模量比,发现La和Zr双掺杂体系的延性（特别是S51,S52,S63和S64）明显改善,且双掺杂体系的延性与杂质原子的相对位置关系不大。布居数、电荷密度分布计算和分析揭示,La和Zr双掺杂γ-TiAl体系各向同性程度提高、延性改善的原因在于体系中Ti4s→3d,Al3s→3p电荷转移明显减少、自由电子数量增多,导致p-d轨道杂化作用减弱,Al（La,Zr）-Ti共价键数量减少和Ti-Ti共价键结合强度显著增强,化学键Al-Al,Ti-Ti和Al-Ti的强度明显趋同、金属性增强。     

锌基合金热力学和相图数据库的建立

利用Visual Basic 6.0软件开发了一套锌基合金体系热力学和相图数据库系统,用于收集、整理锌基合金体系的热力学和相图相关信息.利用该软件系统可以实现对锌基合金体系热力学和相图数据的排序、查询和打印等功能,也可实现数据库的实时更新.探讨了如何实现该软件系统的各项功能,解决了锌合金体系热力学和相图数据人工查询的低效率问题,该数据库软件在锌合金的改性和新型锌合金的设计与开发应用中具有一定使用价值.     

Thermodynamics of Hydrogen Solution and Hydride Formation in Binary Pd Alloys

Some recent thermodynamic results for the solution of H₂ and hydride formation in fcc disordered Pd-rich alloys based on a combined equilibrium-calorimetric technique are reviewed in this paper. This dual approach is more powerful than employing only one of these techniques. Some interesting thermodynamic results connected with these systems are presented, such as minima in ΔH _H and ΔS _H as a function of the H content of the alloys. This paper was presented at the Multi-Component Alloy Thermodynamics Symposium sponsored by the Alloy Phase Committee of the joint EMPMD/SMD of The Minerals, Metals, and Materials Society (TMS), held in San Antonio, Texas, March 12-16, 2006, to honor the 2006 William Hume-Rothery Award recipient, Professor W. Alan Oates of the University of Salford, UK. The symposium was organized by Y. Austin Chang of the University of Wisconsin, Madison, WI, Patrice Turchi of the Lawrence Livermore National Laboratory, Livermore, CA, and Rainer Schmid-Fetzer of the Technische Universitat Clausthal, Clauthal-Zellerfeld, Germany.     

镀锡AgCuZnSn钎料熔化特性的热力学分析

以BAg50CuZn钎料为基材,采用电镀热扩散组合工艺制备了镀锡AgCuZnSn钎料。为了揭示镀锡银钎料的热力学特性,借助差示扫描量热仪(DSC)测定了镀锡银钎料的熔化温度,运用热分析动力学中的非等温微分法和积分法分析了镀锡银钎料的相变热力学特性,并利用金相显微镜和X射线衍射仪(XRD)对钎料熔化后润湿界面的显微组织和物相进行了分析。研究表明,随着Sn含量升高,在吸热峰镀锡银钎料由固态向液态转变的温度区间变窄,非等温微分法和积分法得到的钎料相变活化能均逐渐增大。在Sn含量为7.2%时,镀锡银钎料的相变活化能和指前因子最大,分别为555.56kJ/mol、1.41×10~(32),此时镀锡银钎料相变速率方程的表达式为:k=1.41×10~(32)exp(-5.56×10~5/RT)。7.2%Sn含量的镀锡银钎料在304不锈钢表面熔化后,润湿界面组织主要由Ag相、Cu相、CuZn相、Cu_5Zn_8相、Cu_(41)Sn_(11)相、Ag_3Sn相组成。     

Phase Selection in High-Entropy Alloys: From Nonequilibrium to Equilibrium

High-entropy alloys (HEAs) have been investigated considerably in the last decade. The phase selection in HEAs has attracted much attention recently, especially on forming of the solid solutions. Up to now, phase diagrams of most HEAs are still not well developed, and the empirical phase selection rules play an important role in HEAs area. In this brief review, the physical factors controlling the phase stability in HEAs are discussed, and the phase selection rules are identified. Different from previous results, the rules on equilibrium phase selection within a certain temperature range are carefully reviewed and presented in this article.     

金属－类金属非晶态合金的结构模型

有模拟和计算的方法，确认了构成金属－类金属非晶态合金的菱面体单元结构（ＲＵＳ），并根据三条原则（类金属原子首先位于大八面体中心；除大八面体中心和其棱中心处的类金属原子之间可以存在一个类金属－类金属键外，其它位置处的原子之间不允许存在类金属－类金属键；同一成分，具有多种类金属原于排列方式时，取金属－类金属键最多的情况），找出了各种ＲＵＳ中类金属原子的可能分布位置、所对应的金属－类金属键数和类金属成分。建立了各种分布情况下，每个类金属原子平均所占金属－类金属键数与类金属含量的关系图。结果表明，菱面体单元结构只有８种形式，即（１：１），（２：１）…（８：１）ＲＵＳ，其成分范围（ａｔ％）分别为１５．０９～３０．１９，１２．５０～３０．００，１０．６７～３２．００，９．３０～２９．７７，８．２５～３２．１３，７．４１～３１．０５，６．７２～３０．１７和６．１５～２９．４４。平均键数最大值所对应的类金属含量（ａｔ％）分别为２７．１７，２５．００，２３．１７，２２．３３，２１．４４，２０．７４，２０．１７和１９．６９。     

Structure and Properties of Ti-C Alloys

The mechanical properties of Ti-C and Ti-C-O alloys can be altered by heat treatments to dissolve or reject carbon from solid solutions. The maximum strength is obtained by annealing just below the peritectoid temperature. Quenching from the β-carbide field results in softening. Impact behavior is influenced by the extent of solution of interstitials.     

Elevated-Temperature Al Alloys for Aircraft Structure

Elevated-temperature powder metallurgy (P/M) aluminum alloys are being developed to replace titanium aircraft structure materials for operation in the 300–600°F temperature range. Typical mechanical properties ofP/M Al?Fe?Ce and Al?Fe?V?Si alloys are superior to those of conventional materials, and cost savings of fifty to seventy percent have been projected for these alloys which can be fabricated and processed using methods similar to those used in the production of conventional aluminum.     

高纯铝硅合金的组织遗传研究

应用光学金相研究了高纯铝硅合金中硅相的组织遗传规律.结果表明:硅原料的纯度不同,配制得到的Al-12.5％Si中间合金中共晶硅的尺寸形貌也不同,用纯度为99.996wt％的硅配制的中间合金其共晶硅比纯度为99.85wt％的更细小、均匀.Al-12.5％Si中间合金中共晶硅的尺寸形貌会影响Al-1.0％Si合金中硅的存在状态,即存在硅相的组织遗传性.