1. Introduction
Aluminium alloys form one of the most widely used groups of materials in existence and they make products with wide ranging areas of application. In terms of experimentally determined phase equilibria, researchers such as Phillips and Mondolfo have produced detailed reviews of the literature which provide industry standard publications. The reviews are based on extensive work done on binary and ternary phase diagrams and many of the key features of the phase diagrams are still accepted today.
However, although some important Al alloys are based on ternary systems (for example the 356/LM25 casting alloy based on AI-Mg-Si)，they inevitably include small amounts of Cu, Mn,Fe, Ti etc., all of which can significantly modify the castability and final properties of the final product. The situation is exacerbated by the use of scrap material. It is therefore very useful tobe able to predict phase equilibria in multi-component alloys. A means for doing this is provided by the CALPHAD method.The present paper provides a review of some of the published applications that have been made to A1 alloys and looks forward to potential advances that may be made in the near future.
2. The CALPHAD method
The CALPHAD method has now become a well-established route for predicting phase equilibria in multi-component alloys .Its scientific basis lies in the mathematical description of the Gibbs energy of the various phases that exist in an alloy system.Minimisation methods are then applied so that the mixture of phases providing the lowest Gibbs energy for the alloy of choice is calculated. Thermodynamic calculations have often been perceived as rather theoretica and applicable only to simple systerns. However, verification of CALPHAD predictions against mufti-component alloys of many types has shown that the CALPHAD method can provide results that are very close to exnerimental observation.
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