4GPa超高压凝固Mg-6Zn-3Y合金的凝固组织及相分析

利用X射线衍射仪、扫描电镜并配合能谱分析研究了Mg-6Zn-3Y合金4 GPa超高压凝固组织.结果表明:在4 GPa超高压条件下凝固时,实验合金的凝固组织得到显著细化,基体α-Mg相的晶格间距有所减小;Zn在基体α-Mg中溶解度大幅提高,Y不溶于基体α-Mg;实验合金凝固组织中出现呈对称性的四瓣或六瓣花的初晶Y固溶体,该初晶花瓣形貌完整、尺寸较大,显示其充分自由生长;先发生的共晶反应的共晶组织为成“簇”分布的共晶团,共晶相呈点状或棒状;后发生的共晶反应的组织为离异共晶.超高压凝固显著地改变了实验合金的凝固过程.     

Al-Ni-Y三元共晶合金高压凝固组织

利用光学显微镜,扫描电镜,X射线衍射仪对不同压力(2,4,6 GPa)下凝固的Al-1Ni-3Y(%,原子分数)共晶合金组织形貌和相组成进行研究,并且与常压条件下合金凝固组织进行对比。实验结果表明,与常压凝固相比,在超高压力条件下凝固的合金的显微组织形貌发生了很大的改变,但是合金的相组成没有发生变化。常压凝固的合金具有共晶团组织,而高压下凝固的合金具有枝晶状亚共晶组织。高压凝固合金显微组织中出现了大量的初生α-Al相,这表明高压条件下凝固的合金共晶点发生偏移,使得常压共晶成分的合金在高压下变成亚共晶成分合金。同时,共晶组织的形貌发生了很大变化,常压下凝固的合金的组织为Al3Y相与α-Al相形成的菊花状的二元共晶和Al23Ni6Y4相与α-Al相形成的层片状的二元共晶,而高压下这两种共晶组织逐渐转化为离异共晶组织。随着压力的增大,共晶第二相的体积分数减小,α-Al的晶格常数增加。     

定向凝固Al-Ni-Y三元共晶合金的相组成与凝固特征

在5 K.mm-1温度梯度下,选用1,5,10 mm.min-1三种拉速率对成分为96.0%Al,1.0%Ni,3.0%Y的三元共晶合金进行定向凝固实验,研究下拉速率对合金组织演化的影响规律。通过X射线衍射和光学显微镜分析表明合金由α-Al相、Al3Y相、Al23Ni6Y4相三相组成。当下拉速率为1 mm.min-1时,合金组织呈现三相共晶结构,纵截面有定向凝固趋势;下拉速率为5和10 mm.min-1时,合金组织演变成两种二相共晶:一种是Al3Y相与α-Al相形成菊花状的不规则二相共晶组织,另一种是Al23Ni6Y4相与α-Al相形成层片状的规则二相共晶组织,纵截面上均有明显的定向凝固特征。     

铈在共晶铝硅合金中分布不均匀性的研究

应用放射性强度计数法和自射线照相法,测定了铝硅共晶合金熔体中不同部位的铈含量及其在微观组织中的分布。结果表明,铈的分布存在着宏观及微观偏析,并随铈含量增加而加剧。     

稀土对锡铅共晶合金定向凝固组织的影响

同稀土含量地锡铅共晶合金定向凝固组织的影响，发现稀土的加入使片间距减小，片支断续、不规稀土量增加使结晶组织向胞晶转变，且凝固过程中由于稀土的“亲Ｓｎ”作用，使锡铅共晶点偏移，促进初生富铅相生成，出现亚共晶生长层；稀土化合物对锡铅的凝固过程几乎没有影响。     

电弧熔炼过程中LaFe_(13-x)Si_x合金的凝固组织和相形成研究

研究了电弧熔炼过程中LaFe13-xSix合金的凝固行为。应用XRD和扫描电镜分析了合金组织相组成和结构。结果表明:电弧熔炼铸锭随温度梯度出现分层;La(Fe,Si)13(简称:1∶13)相是包晶反应生成的,冷速和硅含量变化对合金的凝固行为有很大的影响,当Si含量x≤1.0时合金显微组织由α-(Fe,Si)相和共晶相La Fe Si(简称:1∶1∶1)相组成,α-(Fe,Si)(简称:α-Fe)相为主要相,随硅含量增加1∶1∶1相增多;x≥1.5时由α-Fe相、1∶13相和1∶1∶1相组成;随x增加1∶13相为主要相,1∶1∶1相减少;当x≥2.0时显微组织中1∶13相作为初生相析出,且随温度梯度和硅含量变化1∶13相的形貌不同。     

稀土对镁-铝合金抗热裂性能的影响及其机制

研究了稀土（0.1%～1.2%,质量分数）对Mg-Al合金抗热裂性能的影响及其机制.结果表明： 往Mg-Al合金中添加稀土后,合金的抗热裂性能显著下降,其原因可归为： 稀土引起了Mg-Al合金晶粒粗化,使得热裂纹萌生所需的断裂应变降低;稀土减少了Mg-Al合金中的共晶组织,缩短了枝晶通道保持开通的时间,不利于合金进行补缩;而且稀土还提高了共晶反应的温度,使得凝固后期枝晶间液膜的强度有所下降;当α-Mg枝晶连成骨架时,分布在枝晶间的Al11RE3相容易堵塞枝晶通道,增加了合金补缩的难度;Al11RE3相与α-Mg基体的凝固收缩率不同,容易产生凝固收缩应力,促进热裂纹的萌生.     

掺杂元素对铝-硅共晶合金凝固过程的影响

国内外学者对掺杂元素对Al-Si共晶合金的影响进行了大量的研究,这些研究大都侧重于研究变质后的结果,如变质后的晶体结构形态以及掺杂元素对结构形态的影响,再根据变质结果反过来推测可能的变质机理,但对掺杂元素对Al-Si合金凝固过程本身的影响的研究却很少.本文拟采用差热分析法(DTA)和步冷曲线热分析法研究Na、Sr元素对Al-Si共晶合金凝固过程的影响,以探讨Al-Si共晶合金的成核机理。     

镧增加铝合金熔体氢含量的实验分析

采用第一滴气泡法和减压凝固法分析测量了一定量的稀土镧加入前后的铝硅合金熔体氢含量和铝硅合金凝固试样剖面的针孔和气孔的变化，发现镧的加入量超过一定量(0．3％)时，铝合金熔体中的氢含量增加，铝合金凝固试样的针孔和气孔增多。可以认为：一定量的稀土镧引起铝合金增氢现象的原因是镧中含有氢。同时，讨论了镧中氢的来源和含量对铝合金中氢的影响。     

稀土对近共晶Sn60-Pb40软钎料合金凝固组织及高温力学性能的影响

通过加入微量稀土元素改善了软钎料合金的力学人晶Ｓｎ６０－Ｐｂ４０合金的高温接伸强度提高７０％左右。通过对共晶组织凝固过程的分析,发现稀土元素的“亲Ｓｎ”现象导致固液两相交汇点接触角的变化,并最终促使共晶组织直接在先析出富Ｐｂ相上生长,从而抑制了原始组织中粗大的富Ｓｎ相晖圈的出现,实现了金相的均匀化。     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

物质分配系数的测定实验改进

实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。