Comprehensive Assessment and Computerized Prediction of Phase Diagrams

1 Comprehensive Assessment and Computerized Prediction of Phase Diagrams 

Phase diagrams describe the phase relations in equilibrated systems of chemical substances. The determination of phase diagrams is one of the commonest research topics in physical chemistry. After about more than one hundred years work, a huge amount of experimental data has been accumulated. These experimental data have been recorded into many handbooks and databases. They are widely used in daily research work, plant design and other practical work in chemistry, chemical technology and materials science. 

On the other hand, it is unfortunate that not all phase diagrams published in literatures are completely reliable. Some of them are in controversy among different authors because their experimental results are contradictory with each other. Some of them are not believable because their results are contradictory to phase rule or thermodynamic principle. And still others are also not believable because the conclusions of the authors are based on unreliable experimental data. For example, some authors used polythermal visualization method to determine phase diagrams, and concluded the existence of intermediate compound based on some small turning point of liquidus curve. Actually this is unreliable because the small turning point may be induced by small experimental error of the polythermal visualization method. In order to make the published materials more reliable, it is necessary to do systematic assessment work to eliminate or correct the unreliable data from the databases or handbooks. Up to now, the thermodynamic method for the assessment work of phase diagrams has given very plentiful results [83]. 

But it is still not enough if we use this method only. Thermodynamic method cannot make prediction of new phase formation because the thermodynamic function of unknown intermediate compound is not available. 

Strictly speaking, the most reliable method of phase diagram assessment should consist of the following three steps  

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