Development of Extruded Al-Ce and Al-Ce-Mg Alloys for Aerospace Applications

Al-Ce alloys have been recently considered a favorable candidate for aerospace applications due to their thermal stability at relatively high temperatures. We show that warm extrusion can significantly increase the strength and ductility of Al-Ce and Al-Ce-Mg alloys. The extruded Al-10Ce alloys were strengthened by coherent nano size Al11Ce3 precipitates, which led to a room temperature tensile yield strength of 185 MPa, ultimate tensile strength of 248 MPa, elongation of 20%, and fracture toughness of 55.42 kJ/m2, higher than that of the cast samples. Grain refinement and strain hardening were shown through EBSD and XRD analyses to contribute to more than 60% of the strengthening effect. We show that the alloy is not only highly stable (≥99% strength retention after 300 °C 100h exposure) but also remarkably strong at high temperatures (>50% strength retention at 350 °C), superior to that of aerospace grade Aluminum 2618 alloy (<10% strength retention at 350 °C). Mg was shown to further improve the tensile strength of the Al-Ce alloy through the solid solution effect. An extruded Al-10Ce-4Mg alloy was shown to have a room temperature tensile strength of 350 MPa and highly thermally stable with strength retention of ~100% after 300°C 100h exposure. Potential applications such as engine blocks and supersonic aircraft skins are being evaluated for these Al-Ce based alloys.