Measurement of the density and surface tension of Ni-based superalloys in the liquid and mushy states

The densities of three Ni-based superalloys have been measured in both liquid and mushy states by both a modified sessile drop method (MSDM) and a modified pycnometric method (MPM) for alloys CMSX-4 and CM186LC, and for CMSX-10 alloy by MSDM only. The surface tensions of liquid CMSX-4, CM186LC, and CMSX-10 superalloys were measured using the sessile drop method. All measurements were carried out in a highly purified argon atmosphere with the oxygen partial pressure of less than 10⁻¹⁹ MPa in the gas outlet. The densities of all superalloys in both liquid and mushy states were found to decrease with increasing temperature. The volume thermal expansion of each superalloy in the mushy state was found to be higher than that in the liquid state. The densities determined by different methods have been critically assessed and recommended values in both liquid and mushy states are given as a linear function of temperature for the three Ni-based superalloys. The surface tension of liquid CMSX-4 superalloy was found to decrease with increasing temperature, while that of liquid CMSX-10 superalloy increases with increasing temperature. The wetting behavior of liquid CM186LC on the alumina substrate was found (1) to differ significantly from that of CMSX-4 and CMSX-10 and (2) to vary with time. A HfO₂-rich layer was found in the contact area of CM186LC with the alumina substrate, which could lead to some uncertainty in the value obtained for the surface tension determined for CM186LC.     

Gel-Forming Characteristics and Rheological Properties of Kefiran

A water soluble polysaccharide “kefiran” produced by Lactobacillus kefiranofaciens was examined for its gel-forming and rheological properties. Kefiran (3%) formed gel in the presence of ethanol (4–10%). The gel strength in 8% ethanol was comparable to that of 3% gelatin gel in water. Addition of casein (3%) increased gel strength 1.5–2.0 fold. The unique properties of kefiran may make it a useful food additive.     

Carburization and desulphurisation of the semi‐steel during plasma heating

Experiments were carried out on the carburisation, desulphurisation and temperature rise of the semi‐steel in a plasma induction furnace. Influences of many factors, such as power supply, structure and positioning of the plasma torch and bottom‐blown‐gas stirring, on heating efficiency and melt temperature distribution were studied. During carburisation of the semi‐steel, plasma heating could effectively control the melt temperature, consequently, the carbon mass content of semi‐steel increased from 1.92 to 4.58 % with the utilisation efficiency of carbon reached up to 61.57 %, and the desulphurisation ratio could be beyond 66.58 %.     

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.     

用改良密度法精密测量熔融Ni-Ta二元合金的液态密度

用改良密度法对熔融Ni—Ta二元合金的液态密度进行了精密测量。结果表明：熔融Ni-Ta二元合金的密度随温度的增加而减少，但随合金中钽浓度的增加而增加：熔融Ni-Ta二元合金的摩尔体积随温度和合金中钽浓度的增加而增加，并对钽在熔融Ni-Ta二元合金中的偏摩尔体积进行了计算。     

Measurement and Analysis of Density of Molten Ni-W Alloys

1IntroductionNi-based heat-resistant superalloys are widely usedto make critical components in gas-turbine engines,suchas bladeetc.But they are very hard and difficult to bemachined,the net-shape machining of these materials isveryimportant.Computer simul…     

Prediction of the densities of liquid Ni-based superalloys

The molar volume of nickel and the partial molar volumes of Cr, Co, W, Ta, Al, Mo, and Re are computed from the densities of liquid nickel and liquid Ni-based binary alloys measured by the modified sessile drop method (MSDM) and the modified pycnometric method (MPM). The molar volumes of Hf, Nb, and Ti are calculated from the literature density values of these elements. A prediction model for the densities of liquid Ni-based alloys is developed based on the obtained molar/partial molar volumes of the elements in liquid Ni-based alloys. The validity of this model is verified by the density data of liquid Ni-based ternary (Ni-Co-Al), quaternary (Ni-Co-Al-Cr, Ni-Co-Al-Mo, and Ni-Cr-Al-Mo), and commercial alloys measured by both MSDM and MPM. It is also verified by the density values of liquid Ni-based commercial alloys in the literature. It has been shown that the present model can provide reasonable estimation for the density and its temperature dependency of liquid Ni-based alloys. The difference between the predicted value and the measured/cited value is within ±2.5 pct.