Directional solidification of Al-Al3Ni eutectic alloys in an aerogel furnace

Directional solidification experiments of eutectic Al-Al3Ni alloys have been performed using a new facility named ARTEMIS. This facility allows a good control of the solidification parameters, especially the velocity of the solidification front and the temperature gradient ahead of the solid-liquid interface. On vertical cuts through the samples the distance of the Al3Ni fibers lambda was measured and plotted versus the soldification velocity. The results fit to the Jackson and Hunt prediction of lambda*v(2) = const. The microstructure of the solidified Al-Al3Ni alloys show clear differences between samples solidified with constant and those solidified with variing solidification parameters. These differences are analysed with various techniques and are discussed.