Density Measurement of Liquid Ni-Ta Alloys by a Modified Sessile Drop Method

The density of liquid Ni- Ta alloys was measured by using a modified sessile drop method. It is found that the density of the liquid Ni- Ta alloys decreases with the increasing temperature, but increases with the increase of tantalum concentration in the alloys. The molar volume of liquid Ni- Ta binary alloys increases with the increase of temperature ancl tantalum concentration.     

Mechanism of α-Cr precipitation and crystallographic relationships between α-Cr and δ phases in Inconel 718 alloy after long-time thermal exposure

To study the precipitation mechanism of α-Cr phase in Inconel 718 alloy, the samples after long-time aging at 650 and 677℃ were examined by microstructural observations and chemical phase analysis methods. Combining the thermodynamics and kinetics calcula-tion results, α-Cr always precipitates in the vicinity of δ phase, because δ phase rejects Cr into theγ-matrix when growing. The selected area diffraction patterns confirm that the crystallographic relationships of α-Cr with δ phase are (010) δ//(-110)α -Cr and [100] δ//[111] δ-Cr. A graphic model is also presented to show the crystallographic relation between α-Cr and δ phases.     

Atomic volumes and volume functions for Ag-Cu alloys

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添加W对Ti-Al-Cr-Nb铸态合金高温变形的影响

通过非自耗电弧熔炼及氩气保护浇铸方法，合成不同W含量的Ti-Al-Cr-Nb合金。采用高温拉伸测试及显微组织观察，研究添加W对Ti-Al-Cr-Nb铸态合金的显微组织及其高温变形影响。研究结果表明：W的添加使Ti-Al-Cr-Nb合金的铸态组织得到细化；在800℃时基体合金的伸长率从0．62％提高到90％；在高温变形过程中，添加W使Ti-Al-Cr-Nb铸态合金的最大伸长率从620％降低到200％，而最大伸长率相应的温度从850℃增大到1050℃。不同W含量的Ti-Al-Cr-Nb铸态合金在800～1100℃的高温变形机制主要是晶粒滑动，而添加W使晶粒滑动的协调过程由晶界扩散转化为体扩散。     

甲苯二异氰酸酯相关合成体系密度的测定与关联

甲苯二异氰酸酯是重要的有机中间体,为了提供其相关合成反应的工业化设计所必需的密度、超额体积等关键物性数据,选定基础原料甲醇、乙醇、氨基甲酸甲酯为研究对象．分别用激光法测定了常压下甲醇＋氨基甲酸甲酯和乙醇＋氨基甲酸甲酯体系在293．15、308．15K下固体溶质在液体中的溶解度,用间接测量法得到了相应条件下体系的混合密度,然后通过密度进一步计算得到了超额体积．对于上述体系,不同条件下各混合液的过量体积均为负;溶液组成一定时,超额体积随着温度的增加而减小;体系温度一定时,超额体积随着氨基甲酸甲酯摩尔分数的增加而减小．同时,对于不同温度下甲醇＋氨基甲酸甲酯、乙醇＋氨基甲酸甲酯体系密度与组成的关系,超额体积与组成的关系进行了线性关联,回归所得模型系数的最大标准偏差小于0．5％;用Redlich-Kister方程拟合了不同温度下的超额体积与组成的关系,回归所得模型参数的最大标准偏差小于5％．结果表明模型方程可适用于回归上述体系的物性数据．     

Ni-W-P/Ni-P合金的化学沉积试验研究

通过硬度测量和耐蚀试验,并采用扫描电镜／能谱、X射线衍射以及金相分析,研究了化学沉积Ni—W—P和Ni—P合金。结果表明：在镀态下,非晶态Ni—W—P沉积层的硬度低于非晶态Ni—P的硬度,但其耐蚀性优于Ni—P。当沉积层的含W量基本不变时,降低P含量所获得的纳米晶沉积层具有极高的硬度,加之与基体牢固的结合强度及其达到的30μm厚度为齿轮减速器的齿面硬化提供了可能性。而对于高压液压阀工作表面的防腐及抗冲蚀则宜采用非晶态Ni—P沉积层。     

熔盐电沉积法制备铝钙合金中的反电动势实验研究

铝钙合金是理想的脱氧、脱碳、脱硫剂,在冶金工业中作还原剂和添加剂,起到去硫脱氧及净化作用。以易得的CaO代替了CaCl2为原料电解,以石墨为阳极,上浮铝液作为阴极,电解温度在740℃下,在CaCl2-CaF2-BaF2体系中熔盐电解法制得到铝钙合金的过程。采用熔盐电解监控仪测量电解过程中的反电动势、槽电压、电流等工艺参数及电解波形图,通过电位控制法调节Li2CO3的加料周期,重点对反电动势进行了深入的探讨。研究发现,反电动势和槽电压均随阳极电流密度增加而增加,但当电流密度超过0.3 A/cm2以后,反电动势和槽电压增长趋势减缓;临界电流密度经测量为2.548 A/cm2;加入1%CaO后反电动势降低0.5 V,通过控制电位法测得加料周期为30 min     

低活性Fe-Cr-Mn(W,V)合金相稳定性的实验与热力学计算

采用实验和Thermo-Calc热力学计算方法对4种不同成分的Fe—Cr—Mn(W，V)合金(1#、2#、3#、4#合金)的相稳定性进行了研究．实验结果表明，4种合金在623K、673K和773K下时效200h后的主导相为较稳定的奥氏体相．基于热力学自由能的Thermo—Calc计算结果表明：4种合金在实验对应温度下的金相组织为稳定的奥氏体相，计算结果与实验结果有较好的一致性．     

Effects of Trace Silver and Magnesium on the Microstructure and Mechanical Properties of AI-Cu-Li Alloys

The effects of trace silver and magnesium additions on the microstracture and mechanical properties of the Al-Cu-Li alloys were investigated. The experimental results indicate that the effect of combined additions of Ag and Mg is the most obvious , the next is that of individual addition of Mg , and that of individual addition of Ag is the least. The addition of Ag and Mg in Al-Cu-Li alloy accelerates the precipitation of T1 and results in increasing the ageing hardness and strength. Prior cold work significantly improves the tensile strength by enhancing T1 precipitation in all the alloys investigated.     

La(Ni,Sn)5+x (x=0～0.35)贮氢合金的晶体结构与电化学性能

系统研究了La(Ni,Sn)_5+x（x=0~0.35) 无Co贮氢合金的化学计量比对其晶体结构及电化学性能的影响.X射线衍射分析仪（XRD）分析表明，上述合金均为单相CaCu₅结构.但在过计量比(x>0)合金的结构中，有部分1a位置元素（La）的原子被沿c轴定向排列的Ni-Ni“哑铃”对所替代，且其替代La原子的分数随x的增大而增多，从而导致合金晶胞的c轴及c/a比值明显增大，晶胞体积有所减小，并显著降低了合金的吸氢体积膨胀率.电化学测试表明，增大x值可使合金的循环稳定性得到显著提高，但也使合金的最大放电容量和高倍率放电性能有所降低.研究发现，由于合金的化学计量比增大会使其结构中含有较多的Ni-Ni“哑铃”对，合金的抗吸氢粉化能力得到了明显的改善，从而使合金在充放电过程中的反应比表面积有所减小、腐蚀速率得到抑制、循环稳定性得到显著提高.但合金反应比表面积的减小也导致了电极反应的速率的减小，从而使其高倍率放电性能有所降低.     

Densities of methanol＋trimethyl phosphate binary mixtures from （293.15 to 333.15）K and viscosities of trimethyl phosphate from （283.15 to 373.15）K

Densities of methanol+trimethyl phosphate binary mixtures were measured over a temperature range of (293.15 to 333.15)K at atmospheric pressure. From these data, excess molar volume(VE) was calculated. Viscosities of trimethyl phosphate were also measured over a temperature range of (283.15 to 373.15)K and the data were fitted to the Andrade equation. The density data were fitted to a second-order polynomial. The excess molar volumes were fitted to the Redlich-Kister equation using a nonlinear regression method. Results show that the density and viscosity gradually decreases with the increase of temperature.