Microstructure of Gravity-Cast and Suction-Cast Aluminium–Cerium-Based Alloys

The microstructural evolution of binary, ternary, and quaternary Al–Ce-based alloys solidified under different conditions was investigated. Three alloys, Al–12Ce, Al–12Ce–4Si, and Al–12Ce–4Si–0.4 Mg alloys (all in wt.%), were gravity cast and suction cast. The alloys were prepared by melting together commercially pure aluminium ingots, Al–20Ce master alloys, Al–20 Mg master alloys, and Al–50Si master alloys in appropriate ratios. The gravity-cast alloys were molten at 780 °C in a graphite crucible, degassed, and cast in mild steel moulds. The suction-cast alloys were prepared in a vacuum arc casting unit equipped with a suction chamber at the bottom of the mould. The gravity-cast alloys were used as the starting material for suction-cast samples of dimensions 3 mm × 10 mm × 70 mm. The alloys were later isothermally heat treated to understand the thermal stability. The research was undertaken to (1) understand the solidification behaviour of Al–Ce alloy and (2) develop microstructure–property correlations at room temperature and elevated temperature. Furthermore, the properties of alloys so obtained are discussed in light of their microstructures. The results are encouraging and could open newer avenues for the development of lightweight aluminium alloys for elevated temperature applications over the existing Al–Si-based alloys.