Critical Assessment 40: A search for the eutectic system of high-temperature cast aluminium alloys

Abstract

A quest for the eutectic system of novel cast aluminium alloys, having high-temperature capabilities, is critically assessed with two potential candidates of Al–Al₃Ni and Al–Al₁₁Ce₃ examined and compared to the presently used Al–Si base. The conventionally cast Al–Al₃Ni and Al–Al₁₁Ce₃ eutectics do not exhibit the anticipated advantage over Al–Si in strengthening retention at temperatures up to 500°C. The promising differences between diffusivities of silicon, nickel, and especially cerium in aluminium, and eutectic melting temperatures, accompanied by high coarsening resistance of Al₃Ni, Al₁₁Ce₃ phases and the eutectic hardness retention are inconsistent with observed similarities in the temperature-related strengthening-reduction of all three eutectics. These findings will help defining the criteria for development of the eutectic system, suitable for future heat-resistant aluminium alloys.