Solution models Redlich-Kister

The third term of Eq. (14), Gxs, is the excess term of the free energy. Although several of the aluminum alloys considered here form ordered intermetallic compounds, a regular-solution type model was used to describe their excess free energy. Gxs is described by the following Redlich-Kister polynomial,... 

An accurate representation of the phase equilibrium behavior is required to design or simulate any separation process. Equilibrium data for salt-free systems are usually correlated by one of a number of possible equations, such as those of Wilson, Van Laar, Margules, Redlich-Kister, etc. These correlations can then be used in the appropriate process model. It has become common to utilize parameters from such correlations to obtain insight into the fundamentals underlying the behavior of solutions and to predict the behavior of other solutions. This has been particularly true of the Wilson equation, which is shown below for a binary system. 

Models incorporating linear composition dependencies to O (the subregular solution model), as well as others allowing for complex composition dependencies, have been developed. The most commonly used model is by Austrian-born American immigrant Otto R. Redlich (1896-1978) and Albert Theodore Kister (d. 2002) of the Shell Development Company in 1948, which is now known as the Redlich-Kister polynomial (Redlich and Kister, 1948). The total Gibbs energy of a binary system, using the Redlich-Kister model is ... 

The descriptions of all ternary systems were combined in one dataset to simulate the phase equilibria in the quaternary Si-B-C-N system. The results of the thermodynamic calculations of individual systems are shown in the corresponding sections. Thermodynamic models used are the Redlich-Kister polynomial [39], extrapolations according to Muggianu et al. [40] and the compound energy formalism [41] to describe the solid solution phases )S-boron, SiBn, SiBg, SiBs and B4+ C. 

In orientation to the crystallographic results [152, 168], Kasper et al. (1996) [33, 34] and Seifert et al. [169] used for the model description of the homogeneity range of boron carbide the sublattice description (hi2> BiiC)(CBC, CBB, BVaB). The sublattice model (B)93(B,C)i2 was used to describe the carbon solubility in j8-boron. The Redlich-Kister parameters for the liquid phase and graphite (ss) and general formula descriptions for the solution phases were accepted from [36]. The calculated optimized phase... 

---