A New Symmetric Model for Predicting Ternary Thermodynamic Properties from its Three Binary Systems

A new symmetric model for predicting ternary thermodynamic properties from its three binary systems has been presented. The application of this new model to the prediction of the ternary mixing enthalpy of Ga-Bi-Sn system and the ternary excess Gibbs energy of AgCl-LiCl-KCl system shows that the calculated results are close to the experimental data.

A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO_4-H_2O and NaF-H_2O binary solutions and NaClO_4-NaF-H_2O ternary solution

A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions and NaClO4-NaF-H2O ternary strong electrolyte aqueous solutions was developed based on the ion and molecule coexistence theory （IMCT）. A transformation coefficient was needed to compare the calculated mass action concentration and the reported activity, because they were usually obtained at different standard states and concentration units. The results show that transformation coefficients between the calculated mass action concentrations and the reported activities of the same components change in a very narrow range. The transformed mass action concentrations of structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions agree well with the reported activities. The transformed mass action concentrations of structural units or ion couples in NaClO4-NaF-H2O ternary solution are also in good agreement with the reported activities in a total ionic strength range from 0.1 to 0.9 mol/kg H2O by the 0.1 mol/kg step with different ionic strength fractions of 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1, respectively. The results indicate that the developed thermodynamic model can reveal the structural characteristics of binary and ternary strong electrolyte aqueous solutions, and the calculated mass action concentrations of structural units or ion couples also strictly follow the mass action law.

Carbothermal reduction process of the Fe-Cr-O system

Understanding the reduction behaviors and characteristics of the end products of Fe-Cr-O systems is very important not only for maximizing the recovery of metals from stainless steel dust but also for the subsequent reuse in metallurgical process. The present work first predicted the possible products thermodynamically when FeCr204 was reduced by C. The reduction behaviors by graphite of three kinds of Fe-Cr-O systems, i.e., FeCr204, Fe203q-Cr203, and Feq-Cr203, were then investigated in 1350-1550℃. Further, the microstructures of final products and element distribution conditions were examined. The results suggest that, thermodynamically, the mass of products for the carbothermal reduction of FeCr204 is a strong function of temperature, and the initial carbon content is used. More Fe-Cr-C solution and less residual carbon content are obtained at higher temperatures and lower no：no ratios （the initial molar ratio of C to O in the sample）. Experimental data show that the sample amount tends to affect the reduction rate, and the residual carbon content strongly depends on nc：no. With regard to the phases present in products during the reaction process, metal carbides tend to form in the initial stage, whereas Fe-Cr-C solution forms when the degree of reduction is sufficiently high.

Mechanism of Ag and Al on improving the glass forming ability of CuZr-based alloys

By a mean field theoretical computation,the equilibrium distributions of additional Ag and Al in the crystalline phase of CuZr-based alloys were determined to occupy the two sublattices of the B2 structure randomly.With the molecular dynamics technique,the effects of Ag and Al on the enthalpy difference（ΔH） between the supercooled melt and the crystalline phase were evaluated.The improved glass forming ability of Cu45Zr45Al10 and Cu45Zr45Ag10 can be attributed to their remarkably smaller ΔH than that of CuZr.The calculated diffusion coefficients are more sensitive to the atomic weight of the component atoms than to their interaction strength.As the component atom with the largest mass,the additional Ag increases the viscosity of the supercooled melt significantly and the experimentally stronger glass formation ability of Cu45Zr45Ag10 than Cu45Zr45Al10 can be well understood.

Distribution of Nb atom in the TiAl+Nb system

Based on MEAM (the modified embedded atom method) potential and an average atom model similar to B-W (Bragg-Williams) method, the distribution of Nb atoms in TiAl+Nb compounds with various composition was calculated. The calculation results showed that Nb atoms prefer to occupy the Ti sublattice of L10 structure for all compounds in question. With increasing atomic fraction of Nb and Al, Nb atoms exhibited a trend of ordered distribution on the Ti sublattice and result in a new L10 derivative superlattice structure.