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

Abstract

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.