Abstract: Design process of A/ADm-BCn type directional eutectic composites was instanced by investigating Al-Mg-Si-Li and Ni-Mo-C-Al systems in this study by thermoanalysis and directional solidification techniques. It was demonstrated that A(D)-BCn eutectic alloys could be obtained more conveniently by using Smith′s thermoanalysis method to trace change of the eutectic Points of A-BCn induced by addition of components D. A/ADm-BCn directional eutectic composites could be produced from directionally solidified A/ADm-BCn alloys after proper heat treatments if components D have higher solid solubility in components A at high temperature and stable of metastable phases ADm could be formed at room temperature.

Key words: solidification temperature scale, stability, directional eutectic composite