Preparation and Growth Characterization of Al2Cu Phase Crystal with the Single Orientation Under Directional Solidification

Through decreasing the sample size, the regular faceted rectangular Al2Cu phase crystal was prepared under directional solidification. Effects of sample size on the microstructure morphologies and orientations of intermetallic Al2Cu phase crystal growth at 10 µm/s have been characterized and investigated. The transverse-section microstructure of primary Al2Cu phase crystal transited from L-shaped pattern to regular faceted rectangular pattern with a single preferred orientation at [001] direction with sample size decreasing. By using the serial sectioning technique, the three-dimensional (3D) microstructure of Al2Cu phase in 0.45 mm sample was observed as rectangular parallelepiped. Moreover, the faceted interfaces of Al2Cu phase crystal were determined as {110} planes. Based on growth characteristics of the Al2Cu phase crystal, a growth mode in different sizes samples under directional solidification was proposed. The experimental results show that a regular microstructure with preferred single orientation can be achieved in small-size sample during directional solidification.