Special algorithms have been developed to calculate important solidification-related thermophysical properties: enthalpy and enthalpy-related data (i.e., specific and latent heat), density, and thermal conductivity for low-alloyed and stainless steels. The algorithms are heavily based on the use of earlier developed phase transformation models, an interdendritic solidification model (IDS), and an austenite decomposition model (ADC), which solve, as a function of temperature, the phase fractions and compositions needed in these calculations. As a result, the thermophysical properties can be calculated at any temperature, from 1600 ЊC to 25 ЊC, taking into account the discontinuities caused by special phase transformations (i.e., ferritic, austenitic and peritectic solidification, ferrite/austenite transformation, and austenite decomposition to various structures) influenced by the steel grade and the cooling conditions.

A mixed-valence state, formally denoted as Fe 2.5ϩ , is observed in the 300 K Mössbauer spectra of the most reduced samples of SmBaFe 2 O 5ϩw . Upon cooling below the Verwey-type transition temperature (T V Ϸ200 K), the component assigned to Fe 2.5ϩ separates into a high-spin Fe 3ϩ state and an Fe 2ϩ state with an unusually low internal field. The separation of the mixed-valence state at T V is also confirmed by magnetic susceptibility measurements and differential scanning calorimetry. A model is proposed which accounts for the variation of the amount of the mixed-valence state with the oxygen content parameter w.

the number of studied alloys is too small (ii) the alloy selection is biased (too much emphasis is put on some specific alloys) Alternative schemes for the prediction of liquidus (iii) the compositional variation of some examined solute temperatures have been tested against a large in the studied alloys is too small compilation of experimental measurements for (iv) some examined solute appears in only a few of the steels ranging from low carbon to stainless steels.studied alloys The best agreement overall was obtained with (v) often, no account is taken of the change in the slope thermodynamic solutions using the IDS (model of of the liquidus surface upon a change of solidification interdendritic solidification) database, although phase. certain empirical equations from the literature wereThe main problem, however, is the simple form of the adequate for low alloyed steels. Version L of the equations. Typically, the equations are more or less linear commercial ThermoCalc thermodynamics package functions of composition and thus applicable to dilute alloys was outperformed for some steel types by the only. In spite of that, they have also been applied to high empirical equations, prompting a reassessment alloy steels, for example stainless steels. In such alloys there of the Fe-Cr-Ni, Fe-Cr-Si, and Fe-Ni-Si systems are numerous chemical interactions between different solutes, used in the IDS database. Additionally, regression which cannot be described with these linear equations. equations were determined from several thousand Therefore, the entire problem should be approached from predictions computed by the IDS thermodynamic a more rigorous, thermodynamic point of view. approach, and these performed almost as well as theIn the present paper, thermodynamic equations are proper thermodynamic approach at a fraction of the considered and applied for the calculation of liquidus temcentral processing unit time, also outperforming peratures in iron based alloys. The main advantage of such the earlier approaches.I&S/1464 equations is that the primary solid phase is also determined. Consequently, different liquidus surfaces can be treated,

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Thermodynamic optimization of the Cu-Al-Sn system is made using classical thermodynamic models for describing the properties of the individual phases of the system. The optimization is limited to the copper-rich corner of the system, the gamma phase of the Cu-Al and Cu-Sn systems being the remotest phase included in the analysis. The data of the pure components and the binary systems are taken from the previously assessed Scientific Group Thermodata Europe (SGTE)-compatible descriptions, although a slight reoptimization of data is first made for the bcc, fcc, and gamma phases of the Cu-Al system and for the liquid and gamma phases of the Cu-Sn system. Next, ternary thermodynamic data are optimized for the ternary Cu-Al-Sn system using the experimental phaseequilibrium data of the literature. The results of the optimization are presented by comparing the original, experimental data with the calculations, and reasonable agreement is demonstrated.

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