Composition Profile and Microstructure Formation of Unidirectionally Solidified Al–4.5 wt% Cu

The composition profile and the microstructure formation of unidirectionally solidified Al–4.5 wt% Cu sample was investigated. The thermal analysis technique determined the vertical Bridgman’s test sample solidification parameters. Characterization of microstructures was conducted with an optical microscope, and Image-J software determined the α-Al area. Energy-dispersive X-ray spectroscopy was used to assess the composition. The composition profile was confirmed with the actual density and micro-hardness value. The results show that the composition of Cu varies between 4.93 and 3.99%, along with the 98.3% drop in the cooling rate. The reduction of Cu composition is in line with the α-Al area, actual density, and micro-hardness value. Two different morphologies of eutectics are found, fine internal fragments in 1.12 to 2.4 °C/s (less than 35 mm) and the lamellar in 0.04 to 0.06 °C/s cooling zone (more than 35 mm).