Improved High-Temperature Performance of Al–Ce–Ni Alloys via Mg Solid-Solution Strengthening

The remarkable thermal stability of Al–Ce alloys makes them promising candidates for structural applications at elevated temperatures. However, further improvement in their mechanical properties is essential for practical deployment. Microalloying offers a viable approach to enhance the mechanical performance of Al–Ce alloys by tailoring their strengthening mechanisms. In this study, a series of Al–10Ce–5Ni–xMg alloys (x = 0, 0.1, 0.3, 0.5, and 0.7 wt.%) were synthesized to investigate the influence of Mg addition on phase stability, microstructural evolution, and hardness. X-ray diffraction revealed Al, Al₁₁Ce₃, and Al₃Ni as the phases present across all compositions. SEM/EDS and optical microscopy confirmed that no Mg-containing intermetallics formed, consistent with Pandat thermodynamic predictions. Polarized optical microscopy indicated notable grain refinement, with an approximately 21% reduction in average grain size at 0.7 wt.% Mg. Vickers microhardness measurements showed increased hardness in both as-cast and thermally exposed conditions, primarily attributed to Mg-induced solid-solution strengthening. Overall, Mg microalloying effectively enhances the mechanical performance of Al–Ce–Ni alloys while retaining their excellent thermal stability.