Cast dilute Al-Zr-Sc alloys are excellent candidates for some high-temperature automotive and aerospace applications where cast iron and titanium alloys are currently the materials of choice. Al-Zr-Sc alloys offer promising strength and creep resistance at temperatures >300 °C, and can be produced affordably using conventional casting and heat-treatment. The industrial applicability of Al-Sc-Zr alloys is limited, however, by the high cost of Sc, motivating the replacement of as much Sc as possible with other solute elements, such as Erbium. Erbium offers a cost-effective alternative to Sc, and improves Al-Sc-Zr creep resistance by enhancing elastic interactions with dislocations.
My project involves the optimization of both the chemical composition and heat-treatment of Al-Zr-Sc-Er alloys to develop Al alloys capable of use in existing automotive and aerospace applications in the 200-400 °C temperature range. The effect of substituting Er for Sc on strength and precipitate evolution is studied by microhardness, electrical conductivity, atom-probe tomography (APT), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-temperature tensile and compressive testing.