贵金属-AI二元合金形成焓的EAM计算

运用嵌入原子方法（ＥＡＭ）计算了贵金属Ｃｕ,Ａｇ,Ａｎ,Ｎｉ,Ｐｄ;Ｐｔ;Ｒｈ;Ｉｒ和ＡＩ构成的８个二元系统的形成焓,计算结果与已有的实验结果以及Ｍｉｅｄｅｍａ理论计算的结果符合得比较好     

贵金属—Al二元合金形成焓的EAM计算

运用嵌入原子方法计算了贵金属Ｃｕ,Ａｇ,Ａｕ,Ｎｉ,Ｐｄ,Ｐｔ,Ｒｈ,Ｉｒ和Ａｌ构成的８个二元系统的殂成焓,计算结果与已有的实验结果以及Ｍｉｅｄｅｍａ理论计算的结果符合得比较好。     

基于Miedema模型Al3X(Sc, Er, Zr, Li)点缺陷形成焓的计算

运用Miedema模型研究了Al3X(Sc,Er,Zr,Li)金属间化合物的形成焓,并结合点缺陷形成理论计算了Al3X空位和反位缺陷的形成焓。结果表明Al-Sc和Al-Er系形成焓较为接近,说明Sc和Er在Al中性质相近。Al-X(Sc,Er,Li)二元化合物中X原子的空位形成焓高于Al原子的空位形成焓,表明Al-X系二元化合物更易形成Al空位。Al3Er反位缺陷形成焓最大,Al3Zr和Al3Sc居中,Al3Li最小。Al3Sc、Al3Er和Al3Zr易于出现空位和反位两类缺陷共存的情形,而Al3Li反位缺陷形成焓明显小于空位形成焓,因而更易形成反位缺陷。     

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.     

碱金属二元合金的形成焓

根据合金组元原子半径不同引起的弹性畸变，运用Ｍｉｅｄｅｍａ理论系统地研究了碱金属元素为基元的二元金金属间化合物和无序合金形成焓。计算结果表明，得到的形成焓同已有的由第一原理赝势处理方法得到的结果符合得很好。     

Ti/Al/Mg/Al/Ti层合板变形行为及断裂形式的原位研究

为阐明Ti/Al/Mg/Al/Ti层合板的变形行为及断裂形式,对轧制态和退火态的层合板进行原位弯曲和拉伸试验,研究组元板和金属间化合物的裂纹萌生和扩展情况.结果表明:无论Al/Mg界面有无金属间化合物,Al/Mg界面分层都是最先出现的断裂形式,因此Al/Mg界面结合强度决定层合板的力学性能.在退火态层合板中,金属间化合...     

锰对Ti－45Al－10Nb合金的组织和性能的影响

研究了Ｍｎ对Ｔｉ－４５Ａｌ－１０Ｎｂ（原子分数）合金铸态组织和１１００℃再结晶组织的影响以及Ｍｎ对于Ｔｉ－４５Ａｌ－１０Ｎｂ合金力学性能的影响。结果表明，Ｍｎ能促进Ｔｉ－４５Ａｌ－１０Ｎｂ合金的再结晶过程，并改善合金的力学性能     

Mg-Ni非晶合金吸氢形成焓随Ni含量的变化及其对自放电的影响

通过电化学实验方法以及Ｍｉｅｄｅｍａ理论模型计算分别获得了Ｍｇ－Ｎｉ非晶合金的吸氢形成焓△Ｈ,两者对比较为接近,说明该模型可被用于估算非晶合金的吸氢形成焓。对形成焓随Ｎｉ含量的变化趋势进行了研究,结果表明,当Ｎｉ含量（摩尔分数）高于５５％时,合金吸氢稳定性随Ｎｉ含量的增加而升高,而当Ｎｉ含量低于５５％时,稳定性的改变恰好相反,此外还分析了这种变化趋势对Ｍｇ－Ｎｉ非晶合金电极的自放电特性的影响,结果     

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.     

Effect of lattice matching degree and intermetallic compound on the properties of Mg/Al dissimilar material welded joints

The welding of Mg/Al dissimilar materials with different filler metal was investigated, and the quantities and kinds of intermetallic compounds were discussed. In addition, the matching degrees between base metal and intermetallic compounds were defined and calculated, and the effect of different quantities of each intermetallic compound on the property of welded seam was investigated. The results indicated that the welded seam was composed of Al₃Mg₂ and Al₁₂Mg₁₇ by Mg/Al directly gas tungsten arc butt welding, and only one intermetallic compound of MgZn₂ formed in the welding seam using Zn and Zn–xAl filler metal. The tensile strengths of the joints increased with the increase of the matching degrees between the intermetallic compounds and the base metal when the welded seam contained different intermetallic compound. Meanwhile, the tensile strengths of the joints are decreased with the increase of intermetallic compound content when the welded seams contained the seam intermetallic compound.     

Friction stir-induced brazing of Al/Mg lap joints with and without Zn interlayer

The interfacial structure and mechanical properties of Al/Mg joints with and without Zn interlayer by friction stir-induced brazing bond have been investigated. The results revealed that the formation of brittle Al–Mg intermetallics could be effectively suppressed by the addition of Zn interlayer and using appropriate welding parameters, which were replaced by α(Mg)+Mg–Zn and Al–Mg–Zn intermetallic. When rotation speed was further increased, Al–Mg intermetallics were formed again at the interface. The shear strength of Al/Mg joints with Zn interlayer was improved by up to ～25% in comparison with those of the joints without Zn interlayer. A mixture of ductility and cleavage fracture occurred on fracture surfaces of Zn-added joints which was different from the cleavage fracture feature of the direct joints.     

Cation transport properties of Li-M-Silicate (M=Mg, Al, Ti) composite compounds

Various crystalline Li-M-Silicate (M=Mg, Al, Ti) composite compounds were prepared and their cation transport properties examined. The extent of reaction was tested under the fixed M:Si molar ratio of 1 by changing the Li molar ratios from 0.1, 0.3, 0.5, 0.7 to 1. The physiochemical properties of the materials obtained were analyzed by using ICP-AES, XRD, TG/DTA and SEM and conductivity measurements were carried out with an LCR meter. According to the results found in the substituted polyvalent Mⁿ⁺ ion and the added lithium contents, each polycrystalline sample showed various crystal structures and conductivity. The highest conductivity was obtained from Li-Al-Silicate compound (Li: Al: Si=0.3∶1∶1), which contains the LiAlSiO₄ transient phase to facilitate free space for the lithium ions mobility in the crystal lattice.     

Ti/Al固相扩散反应行为表征及动力学研究

本研究在Ti和Al均过量时,表征了Ti/Al在520℃~630℃范围内不同时间下的固相扩散反应行为。结果发现,当试样退火46小时后,Ti/Al界面的反应产物为单一相TiAl3,而且TiAl3/Al界面上的TiAl3生长速度比Ti/TiAl3界面上的TiAl3生长速度快。此外,本研究建立了TiAl3生长动力学模型,Ti/Al扩散反应激活能为170.1 kJ/mol,动力学指数为n=0.5,TiAl3生长随时间呈抛物线规律增长,利用Ti/Al复合粉末体作为试验材料,证明了所建立的TiAl3生长动力学方程的正确性。     

钛/铝异种合金电弧熔钎焊接头界面特征及力学性能

采用AlSi5焊丝和交流TIG电弧实现了TC4钛合金和6056铝合金的熔钎焊连接,通过金相显微镜(OM)、扫描电镜(SEM)、能谱分析仪(EDS)和拉伸试验等方法评价了接头界面微观组织特征和力学性能.结果表明,当焊接电流为30,40和60 A时,界面反应层分别呈棒状、块状和锥状分布,过大的热输入使界面产生了粗大柱状金属间化合物层,冷却时在焊接内应力作用下产生了冷裂纹.金属间化合物主要为TiAl3相,Si元素偏聚其内形成过饱和固溶体.接头强度-焊接电流曲线出现了两次峰值强度.焊接电流为30 A时,熔钎焊接头平均抗拉强度为103 MPa.焊接电流为60 A时,电弧形态扩张使能量密度降低,接头强度出现第二次峰值.     

镁/铝层合板FSW接头微观组织及力学性能

文中采用搅拌摩擦焊 (FSW)方法对Mg/Al层合板进行单面、双面对接方式焊接,对接头的微观组织和力学性能进行测试. 结果表明,随着焊接速度和搅拌针旋转速度的增加,焊缝表面成形良好,接头不同区域未见气孔、裂纹等缺陷,物相主要由Mg₁₇Al₁₂,Mg₂Al₃和MgAl等组成,接头部位的晶粒尺寸得到明显细化,产生了动态再结晶,金属间化合物的形成有利于动态再结晶的形核. Mg/Al层合板双面FSW焊接头的拉伸强度和断后伸长率高于单面焊接接头的强度和断后伸长率,主要是由于接头部位金属间化合物的数量和分布不同,抑制接头部位金属间化合物的形成有利于提高Mg/Al层合板FSW接头的性能.