Effect of cooling rate on the 3D morphology of the proeutectic Al3Ni intermetallic compound formed at the Al/Ni interface after solidification

Effect of cooling rate on the 3D morphology and the growth mechanism of the proeutectic Al3Ni intermetallic compound (IMC) that forms at the Al/Ni interface after solidification was investigated by synchrotron X-ray microtomography in combination with EBSD analysis. The proeutectic Al3Ni phase that forms under an average cooling rate of 0.1 K s−1 shows a characteristic faceted growth behavior and presents a typical 3D morphology as partially hollow quadrangular prisms. On the contrary, that forms under an average cooling rate of 10 K s−1 shows complicated dendritic morphology with asymmetrically distributed arms and faceted V-shape groove at the distal end, indicating a gradual transition of the growth behavior from non-faceted to faceted during the solidification process. These results reveal that the morphology of the proeutectic Al3Ni is highly sensitive to the solidification condition so that fine control of the desired morphology may be achieved by carefully manipulating the cooling profile.