A comparative study on the microstructure and performance stability of Cu-Al2O3 and Cu-Y2O3 alloys after high-temperature annealing

This study presents a comparative analysis of the microstructure and performance stability of Cu-Al2O3 and Cu-Y2O3 alloy after annealing at temperatures ranging from 600 °C to 1000 °C. The evolution of grain size, nanoparticle size, and mechanical properties was investigated using transmission electron microscopy (TEM), scanning electron microscope (SEM), electron backscattered diffraction (EBSD), X-ray diffraction (XRD) and mechanical tests. The results indicate a more rapid degradation of yield strength and ultimate tensile strength in Cu-Y2O3 alloy after annealing at a temperature of ≥800 °C, while the mechanical properties of Cu-Al2O3 are relatively stable. The main cause of the decrease in mechanical properties is attributed to the rapid grain growth observed under annealing temperatures of ≥800 °C. Cu-Y2O3 alloy exhibited lower grain size stability, and the activation energy of grain growth was estimated to be 115 kJ/mol, which is lower than that of Cu-Al2O3 but comparable to the value reported in the literature for CuCrZr alloy. In contrast, the activation energies for coarsening of Y2O3 and Al2O3 nanoparticles were determined to be 58.9 kJ/mol and 44.1 kJ/mol, respectively. These results indicate that Y2O3 nanoparticles were found to be more stable than Al2O3 nanoparticles.