The Effect of Adding CeO₂ Nanoparticles to Cu-Ni-Al Alloy for High Temperatures Applications

This work presents the effect of CeO₂ nanoparticles (CeO₂-NPs) on Cu-50Ni-5Al alloys on morphological, microstructural, degradation, and electrochemical behavior at high temperatures. The samples obtained by mechanical alloying and spark plasma sintering were exposed to a molten eutectic mixture of Li₂CO₃-K₂CO₃ for 504 h. The degradation of the materials was analyzed using gravimetry measurements and electrochemical impedance spectroscopy. Different characterization techniques, such as X-ray diffraction and scanning electron microscopy, were used to investigate the phase composition, parameter lattice, and microstructure of Cu-Ni-Al alloys reinforced with CeO₂-NPs. The hardness of the composite was also examined using the Vickers hardness test. Gravimetry measurements revealed that the sample with 1 wt.% CeO₂-NPs presented the best response to degradation with a less drastic mass variation. Impedance analysis also revealed that by adding 1 wt.% CeO₂-NPs, the impedance modulus increased, which is related to a lower porosity of the oxide film or a thicker oxide layer. The microhardness also significantly increased, incorporating 1 wt.% CeO₂-NPs, which reduced with higher CeO₂-NPs content, which is possibly associated with a more uniform distribution using 1 wt.% CeO₂-NPs in the Cu-Ni-Al matrix that avoided the aggregation phenomenon.