A newAerospace generation of Al alloysAl alloy based on the Al–Ce system, with microstructureMicrostructure and properties weakly sensitive to elevated temperatures, is being developed for applications such as thermal engine blocks and supersonic aircraft fuselage components, where high-performance calls for mechanical propertyMechanical properties retention during prolonged exposure to elevated temperature. Cast Al–Ce binary alloys with 10 and 16% Ce were produced by slab and book mold castingCasting and their mechanical propertiesMechanical properties were measured and compared. Slab cast samples were further processed by extrusionExtrusion, which increased strength and ductility by a factor of two. The as-cast and extruded Al–10%Ce showed 99% strength retention after long-term (100 h) exposure to 300 °C, with shorter-duration exposure (10 h) providing a 7% increase in strength. The microstructureMicrostructure and hardness did not change upon longer annealingAnnealing times (up to 400 h), which indicates the outstanding thermal stabilityThermal stability of this class of Al alloysAl alloy. The microstructureMicrostructure of extruded samples observed using EBSD was modeled to determine the effect of the stiffness mismatch between Al11Ce3 precipitatesPrecipitate and the Al matrix on the strain distributionDistribution. It was concluded that the mismatch effect is weak enough for the strain distributionDistribution in the two-phase alloy to be indistinguishable from that in the single-phase alloy. Therefore, the elastic contrast is expected to have little effect on the plastic deformation and fatigue response of these alloys.