Thermodynamic Modelling of High Temperature Systems
Winny Wulandari, Geoffrey A. Brooks, Muhammad A. Rhamdhani, Brian J. Monaghan
Thermodynamic modelling is widely used to predict phase equilibria and solute partitioning in high temperature materials processing. There have been significant advances in computational thermodynamic modelling in the last three decades. A number of thermochemical software packages and databases have been established and developed, offering different features and capabilities. This paper summarises the fundamentals of thermodynamic modelling focusing on multi-component phase equilibrium using Gibbs energy minimisation and solution models. Different thermodynamic packages used by the authors are described and the key features of each package are highlighted. The packages described are Chemix (The CSIRO-SGTE Thermodata System), MTDATA, FactSage, and HSC. An example of thermodynamic modelling on the distribution of impurities in magnesium production using both ideal solution and a random mixing solution models is presented. Using ideal solution model for the condensate from the process, a purity of 98.33 wt% Mg is predicted compared to 99.98 wt% using the alternate solution model. These difference are important because of the repercussions on the development of new routes for magnesium, as commercial grade magnesium requires a purity of greater than 99.95 wt.% This example illustrates both the predictive power of thermodynamic modelling but also the dilemmas associated with dealing with solution behaviour.
Keywords: Thermodynamic Modelling; Thermochemical Software; Solution Model; Magnesium Production