Studying on the morphology of primary phase by 3D-CT technology and controlling eutectic growth by tailoring the primary phase

Abstract Morphology and alignment of the structure determine material properties. In the present work, the morphologies of the typical primary Al2Cu and Al3Ni phases in hypereutectic alloys are studied by 3D-CT technology, and their growth characteristics have been clarified further. The experimental result reveals that the Al2Cu and Al3Ni phases grow with a faceted characteristic at a lower growth rate, and the transition from the faceted phase to the non-faceted phase occurs with the increase of growth rate. It is also found that the application of the temperature gradient or/and the magnetic field is capable of controlling the growth of the primary Al2Cu and Al3Ni phases, and the alignments of the primary Al2Cu and Al3Ni phases remarkably affect that of the Al–Al2Cu and Al–Al3Ni eutectic. This implies that the eutectic phase can be controlled by tailoring the primary phases during imposing the magnetic field or/and temperature gradient. Finally, a simple model of controlling the growth of the eutectic phase by tailoring the primary phase is proposed. The present work can deepen the understanding on the growth characteristics of the Al2Cu and Al3Ni phases and offer a new method to control the eutectic phase by tailoring the primary phase.