Density and surface tension of the Pb-Sn liquid alloys

The maximum bubble pressure method and the dilatometric method were used, respectively, in measurements of surface tensions and densities of Pb-Sn liquid alloys. The experiments were carried out in the temperature range from 573 to 1200 K for the pure Pb, pure Sn, and 7 alloys of the compositions 0.1, 0.2, 0.26, 0.36, 0.5, 0.7, and 0.9 mole fraction of Pb. A straight-line dependence on temperature was observed and fitted by the method of least squares both for the densities and the surface tensions. The calculated density isotherm at 673 K showed a positive deviation from the linearity over the entire range of composition, and the same tendency was seen at 1173 K for compositions higher than X _Pb=0.26. At the lower concentration of Pb, a nearly linear character of 1173 K isotherm was noted. In the case of surface tensions, both at the lowest and the highest temperatures (673 and 1173 K), the deviation from linearity with composition was negative, but deviation decreased with increasing temperature. The isotherms of the compositional dependence of surface tension calculated from the Butler model exhibit good agreement with experimental data.     

Surface tension of liquid Au-Bi-Sn alloys

The surface tension of a promising lead-free solder Au-Bi-Sn alloys was investigated both by the sessile-drop method and calculation. Experimental measurements were carried out for two cross-sections with the constant gold to bismuth ration of 1:1 and 1:2. For all the investigated compositions, decrease of the surface tension is observed with increasing temperature. Meanwhile, the surface tension values were also calculated based on Butler's equation, with using the newest research on thermodynamics data of...     

Anomalous temperature dependence of the surface tension in liquid silver–lead alloys

The surface tension of liquid silver–lead alloys is discussed with special emphasis on the unusual temperature coefficients apparent at certain concentrations. In contrast to most other liquid alloys silver-rich mixtures of silver–lead adopt positive temperature coefficients. This anomalous behaviour is found to be well explained in terms of Butler's model of surface tension. The phenomenological approach of Bhatia and March was applied in semi-empirical manner in order to achieve agreement with the experimental findings. In view of the high concentration fluctuations of the system – expressed in terms of S_cc(0) – the anomalous temperature coefficients find a plausible interpretation. A short critical assessment of the model's general applicability to systems with demixing properties is presented. Qualitatively, both treatments indicate that the unusual temperature dependence of the surface tension is the mere consequence of the thermodynamics of the system.     

Wetting and surface tension measurements on gold alloys

The surface tension and the density of some gold alloys have been measured and their wetting behaviour investigated in relation to different ceramic supports. Relationships between surface tension and density as a function of temperature are proposed.     

Surface tension of liquid Ag-Sn alloys: Experiment versus modeling

The maximum bubble pressure method has been used to measure the surface tension of pure tin and seven binary alloys with concentrations of 15, 30, 40, 60, 75, 87.8, and 96.2 at.% Sn. Measurements were performed at the temperature range from 500 to about 1400 K depending on the composition of the investigated alloy. Densities of the Ag-Sn alloys were measured dilatometrically. The linear dependencies of densities and surface tensions on temperature were observed, and they are described by a straight-line equation. Experimental data of the surface tensions were compared with calculations using Butler’s model, which assumes an equilibrium between the bulk phase and the monolayer surface phase. Excess Gibbs energies of silver and tin necessary in calculations were taken from the optimized thermodynamic parameters reported recently from Tohoku University. It is shown that the calculated surface tension data from the optimized thermodynamic parameters of the liquid phase of the Ag-Sn are in good agreement with the experimental results.     

Surface tension of liquid Ag-Sn alloys: Experiment versus modeling

The maximum bubble pressure method has been used to measure the surface tension of pure tin and seven binary alloys with concentrations of 15, 30, 40, 60, 75, 87.8, and 96.2 at.% Sn. Measurements were performed at the temperature range from 500 to about 1400 K depending on the composition of the investigated alloy. Densities of the Ag-Sn alloys were measured dilatometrically. The linear dependencies of densities and surface tensions on temperature were observed, and they are described by a straight-line equation. Experimental data of the surface tensions were compared with calculations using Butler’s model, which assumes an equilibrium between the bulk phase and the monolayer surface phase. Excess Gibbs energies of silver and tin necessary in calculations were taken from the optimized thermodynamic parameters reported recently from Tohoku University. It is shown that the calculated surface tension data from the optimized thermodynamic parameters of the liquid phase of the Ag-Sn are in good agreement with the experimental results.     

Surface tension and mass density of liquid Cu–Ge alloys

We report a study on the mass density and surface tension of liquid Cu–Ge alloys in the temperature range between the liquidus line and 1373 K. The experiments have been carried out by means of the sessile-drop method. The temperature dependences of both properties are given in terms of linear relations for all alloys under investigation. Both, density and surface tension show remarkable deviations from linear mixing: The density is increased, and the surface tension reduced due to Ge acting as surfactant. The composition dependence of the surface tension is discussed in terms of a simple compound formation model which is well able to relate the results to previous findings on the short-range order of the alloys under investigation.     

铅锡合金表面钝化层的XPS研究

采用x射线光电子能谱(XPS)对铅锡合金表面钝化层的组分与结构进行分析,目的是要确定钝化层中各元素的化学价态和存在形式,并试图明确锡对钝化膜导电能力的影响.结果表明:钝化膜具有分层结构,表层由SnO2,SnO,PbSO4,PbOx(1＜x＜2)和PbOx·Sn1-xO2组成,内层为SnO2,SnO,PbO,PbOx和PbOx·Sn1-xO2.内层钝化膜的导电性优于表层,锡能促进生成电阻远小于PbSO4和PbO的铅的过渡氧化物PbOx(1＜x＜2),从而提高其电导率.但是,内层的物质构成和分布并不均匀,出现了非导电区(极少量)和导电区并存的现象,而外层并没有类似情况发生.钝化膜自外向内含铅量和含锡量均呈上升趋势,含氧量呈下降趋势,锡的增值幅度随母体含锡量的减少而增大,但铅浓度的变化规律与之相反.     

Density and surface tension of dioctylphthalate,silicone oil and their solutions

The surface tension and the density and their dependence on temperature between 20 °C and 80 °C are reported for the system dioctylphthalate-silicone oil (viscosity, 5 cSt) over the complete composition range.     

The rapid prediction of the modification level of Al-Si alloys by surface tension

Both the theoretical analysis and experiments on Al-Si alloys have shown that a relationship between the surface tension and the modification of Al-Si alloys exists. A new method for the rapid prediction of the the modification level of Al-Si alloys by surface tension has been introduced. The quantity of the modifier is found to have the greatest effect, followed by the time of the modif cation and then the temperature. In Al-Si alloys, when the surface tension is above 530 mN/m, the modification level is partial. When the surface tension is between 400 mN/m and 530 mN/m, the modification level is moderate. When the surface tension is below 400 mN/m, the modification level is perfect.     

Density of liquid NiCoAlCr quartemary alloys measured by modified sessile drop method

The densities of liquid NiCoAlCr quaternary alloys with a fixed molar ratio of Ni to Co to Al （x（Ni）：x（Co）：x（Al）≈ 73：12：15） which is close to the average value of the commercial Ni-based superalloys TMS75, INCO713, CM247LC and CMSX-4, and the mass fraction of chromium changes from 0 to 9% were measured by a modified sessile drop method. It is found that with increasing temperature and chromium concentration in the alloys, the densities of the liquid NiCoAICr quaternary alloys decrease, whereas the molar volume of the liquid NiCoAICr quaternary alloys increases. And the liquid densities of NiCoAICr quaternary alloys calculated from the partial molar volumes of nickel, cobalt, aluminum and chromium in the corresponding Ni-bases binary alloys are in good agreement with the experimental ones, i.e. within the error tolerance range the densities of the liquid Ni-based multi-component alloys can be predicted from the partial volumes of elements in Ni-based binary alloys in liquid state. The molar volume of liquid NiCoAICr binary alloy shows a negative deviation from the ideal linear mixing and the deviation changes small with the increase of chromium concentration at the same temperature.     

Heat transfer at the metal/substrate interface during solidification of Pb-Sn solder alloys

Heat transfer analysis during the solidification of lead, tin, and two lead-base solder alloys against two different chill materials (steel and copper) was carried out with and without flux coating on the chill surface. Temperatures at two known locations inside the chill and casting were recorded as the casting started solidifying, and the acquired chill temperature data were used for solving a one-dimensional heat conduction equation inversely to yield the metal/chill interfacial heat flux and chill surface temperature as a function of time. The initial heat flux was high due to good contact at the metal/chill interface. As the casting started solidifying, there was a reduction in the heat flux due to the nonconforming contact at the interface. Chills with flux coating resulted in finer microstructures near the solder/substrate interface compared to those obtained with uncoated chills. The fineness of the microstructure also increased when copper was used as the chill material. The estimated total heat flow was found to be higher with flux-coated and copper chills. This was in good agreement with the finer microstructures obtained near the solder/chill interfacial region for solidification against copper chills and chills with flux coating on their surface.     

液态铝合金表面张力快速检测新方法与装置

表面张力是液态合金的重要物性参数之一,铝合金表面张力与其变质处理效果及充型能力等质量参数密切相关,研究铸造铝合金表面张力快速检测方法及装置,对于开发铝合金熔炼质量炉前实时评价系统具有非常重要的实际意义.介绍了一种液态铝合金表面张力快速测试的新方法和新装置,新方法以固定时间内吹入被测液体的气泡个数以及气泡在生长过程中内部压差变化为信息参数,通过回归公式求解表面张力.基于该方法研制的表面张力新型测试装置由单片机测控单元、探头及其锁紧和升降机构、供气单元等部分构成.采用新装置可在5 s内测得铝合金表面张力,且具有较高的测试精度.     

Surface tension, density, and molar volume of liquid Sb-Sn alloys: Experiment versus modeling

Through the application of the maximum bubble pressure and dilatometric method, density and surface tension were investigated. The experiments were conducted in the temperature range from 583 K≤T≤1257 K. The surface tension was measured for pure antimony and for six liquid Sb-Sn alloys (mole fractions X _Sn=0.2, 0.4, 0.6, 0.8, 0.9, and 0.935 mm²) and measurements of the density were only for alloys. It has been observed that both surface tension and density show linear dependence on temperature. The temperature-concentration relation of both surface tension and density were determined with minimization procedures. The surface tension isotherms calculated at 873 K and 1273 K show slight negative deviations from linearity changes, but the observed maximal differences did not exceed 30 mN · m⁻¹. The surface tension calculated from Butler’s model was higher than the experimental value for most concentrations and also showed curvilinear temperature dependence. The experimental densities and the molar volumes of the Sb-Sn liquid alloys conform very closely to ideal behavior with differences comparable to the experimental errors.     

Surface tension,density, and molar volume of liquid Sb-Sn alloys: Experiment versus modeling

Through the application of the maximum bubble pressure and dilatometric method, density and surface tension were investigated. The experiments were conducted in the temperature range from 583 K≤T≤1257 K. The surface tension was measured for pure antimony and for six liquid Sb-Sn alloys (mole fractions X _Sn=0.2, 0.4, 0.6, 0.8, 0.9, and 0.935 mm²) and measurements of the density were only for alloys. It has been observed that both surface tension and density show linear dependence on temperature. The temperature-concentration relation of both surface tension and density were determined with minimization procedures. The surface tension isotherms calculated at 873 K and 1273 K show slight negative deviations from linearity changes, but the observed maximal differences did not exceed 30 mN · m⁻¹. The surface tension calculated from Butler’s model was higher than the experimental value for most concentrations and also showed curvilinear temperature dependence. The experimental densities and the molar volumes of the Sb-Sn liquid alloys conform very closely to ideal behavior with differences comparable to the experimental errors.     

毛细管法测量液体表面张力的误差分析与特性研究

通过Bashforth—Adams方程获得了真实接触角,在此基础上分析了毛细管法测量液体表面张力的误差来源,解决了这一领域存在的一些争议性问题,并进一步揭示和探讨了毛细管法测量液体表面张力的特性。     

Superelastic tension and bending characteristics of shape memory alloys

The objective of this study was to develop a numerical model of the superelastic behavior of shape memory alloys (SMA) on a macro-scale level. Results from a study on this behavior under tension and pure bending tests are presented and discussed. Two SMA samples were used in the experimental work and subjected to various loading paths in tension and pure bending: a single crystalline CuZnAl alloy and polycrystalline NiTi wire. Bending tests were performed under a pure bending loading condition on a new testing apparatus designed for the specific needs of this study. The experimental part of this study focused mainly on the response of the SMA to the loading paths in a quasi-plastic domain where the deformation mechanism is dominantly governed by the stress-induced martensitic transformation. Experimental results obtained from the NiTi polycrystals by tensile tests indicate that the superelastic SMA exhibits sufficient repeatability useful enough for a modeling task, while similar results obtained from the single crystalline CuZnAl indicate that the same modeling approach is not easily feasible. The facts have been qualitatively verified by the experimental data from pure bending tests, and a further area as study is suggested.     

Heat capacity of liquid and undercooled liquid metals and alloys

Trends in the dependences on temperature and concentration of experimentally determined heat capacities of liquid and undercooled liquid metals and alloys are discussed. A new adiabatic calorimeter for determining the heat capacity of liquid alloys up to 1500 K is described. The ability of several approximations and models to describe the different characteristics of the heat capacity of liquid and supercooled liquid metals and alloys is demonstrated.     

Theoretical calculations of the surface tension of Ag(1−x)-Cu(x) liquid alloys

The surface tension of silver-copper binary liquid alloys is calculated, in the frame work of Eyring theory. The calculations were made for different compositions (mole fraction, x_Cu = 0, 0.2, 0.4, 0.6, 0.8 and 1), in the temperature range 1100-1800 K. The surface tension decreases with temperature increase, at a fixed copper fraction x_Cu, and increases with increasing copper content. The calculated results are appropriately compared with existing literature data.