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The viscosity of CaO-5MgO-Al2O3-SiO2 slag with low silica was measured by rotating cylinder method up to 1823 K. Slag compositions were chosen based on five different levels of SiO2 content between 0 and 11·80%. The MgO content was 5·0%. The mass ratio of CaO/Al2O3 was varied from 0·66 to 1·95. It was shown that viscosity decreased with increasing temperature and decreased with increasing the mass ratio of CaO/Al2O3, following by an increase with further increasing the mass ratio of CaO/Al2O3. The viscosity decreased with the NBO/T ratio increasing, and the trend that flow activation energy changes with the NBO/T ratio of slag was the same as the trend that viscosity changes with the NBO/T ratio. Based on the experimental data as the boundary of the homogenous phase region, the mass triangle model was used to calculate the viscosity of low silica region. [ABSTRACT FROM AUTHOR]

Undercooled solidification of hypoeutectic Ni-3·3 wt-%B alloy has been studied. The microstructure evolution of Ni-3·3 wt-%B alloy indicates that a transition from regular lamellar eutectic to anomalous eutectic exists with increasing undercooling for eutectic transformation. Here, a new model was proposed to describe the cooling curves of undercooled solidification with two-step transformation. Fits of the present model to the cooling curves after different undercoolings show that the predictions of transformed fractions are compatible with the microstructure observation. Furthermore, for hypoeutectic alloy, the size of the primary phase mainly depends on the undercooling for primary solidification, while the fraction of the primary phase mainly depends on the undercooling for eutectic solidification. [ABSTRACT FROM AUTHOR]

By comparing phase fractions upon solidification of Ni-3·3 wt-%B alloy obtained by differential scanning calorimetry (DSC) measurement, microstructure observation and the baseline method, the results show that although as an approximate approach, the baseline method can be used to predict the phase fractions from the cooling curve, and it can reflect the relationship between the transformed fraction, time and temperature simultaneously during solidification, which cannot be obtained from DSC measurement. In addition, the effects of non-constant specific heat and latent heat of phases on the baseline method are discussed and the calibration relationships are deduced. [ABSTRACT FROM AUTHOR]

During the continuous casting of medium carbon steel slabs, stable liquid slag film performance is necessary to ensure that the process runs smoothly. In this paper, the effects of mould flux crystallisation behaviour on the properties of leftover liquid slag films were examined. First, the compositions of the leftover liquid slags of high fluorine, CaO-SiO2-TiO2 and CaO-SiO2-Na2O based mould fluxes after a single crystalline phase was separated were calculated. Then, the viscosity, melting temperature, break temperature and degree of crystallisation of each leftover liquid flux were measured. The results revealed that the properties of leftover liquid slag films of CaO-SiO2-TiO2 and CaO-SiO2-Na2O based mould fluxes are not as stable as those of high fluorine films after crystallisation. This paper provides a new method for developing fluorine free mould fluxes and for determining the most suitable type of crystalline phase that should be utilised in the continuous casting of medium carbon steel slabs. [ABSTRACT FROM AUTHOR]

Microstructure refinement of ternary eutectic Fe40Ni40B20 alloy in undercooling and rapid cooling solidification has been studied. In natural cooling conditions, two kinds of microstructure refinement take place with increasing undercooling. For melts with the same undercooling, the as solidified microstructure refines first and then coarsens with increasing cooling rate. On this basis, repeatable experiments show that the combination of melt undercooling at ~50 K with Ga-In alloy bath rapid cooling produces very fine eutectic cells (~5 μm in diameter with the lamellae spacing <100 nm). This indicates that an appropriate initial melt undercooling combined with a proper cooling rate is a potential way to produce a bulk nanostructure in ternary Fe40Ni40B20 alloy. [ABSTRACT FROM AUTHOR]

A simple method was proposed to calculate the essential parameters correlated with the critical nucleation frequency of undercooled metals and alloy melt. Numerical results show that the calculation accuracy from this method can be improved using the experimental data either with high undercooling or with low undercooling range (the difference of undercoolings between two solidification events). The calculations of the interfacial energy for high undercooling of silver and of the catalytic factor f(h) for high undercooling of Al, Cu and Al-30 wt-%Cu alloy indicate that the results are consistent with the experimental measurements and with the results of Jian's model [Metall. Trans. A, 2001, 32A, 391-395]. In addition, by analysing the differential scanning calorimetry data of pure Sn subjected to different cooling rates, similar values of catalytic factor f(θ) are obtained. This further indicates the validity of the current method. [ABSTRACT FROM AUTHOR]

Assuming constant rates for nucleation and growth and neglecting thermal gradient in the melt, an analytical approach to describe the undercooled solidification was proposed in terms of ja(x) function. This approach was adopted to study the solidification of undercooled Ni-B alloy. With increasing melt undercooling, good model fits to recalescences arising from the solidification of the primary and eutectic phases were obtained. The fitting results are consistent with the structure evolution upon solidification. [ABSTRACT FROM AUTHOR]