Effects of He irradiation on the microstructures and mechanical properties of Al2O3–ZrO2–ZrC ceramic composites.

In this study, the irradiation response of Al 2 O 3 –ZrO 2 –ZrC ceramic composites under 500 keV He ion irradiation at room temperature has been investigated. The microstructure evolution was studied by grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM), while the hardness was assessed using the nanoindentation method. The results showed that the composites consisted of α-Al 2 O 3 , t-ZrO 2 , and ZrC phases, and no phase transformations were observed. However, a marginal degradation of structural crystallinity and lattice swelling occurred after irradiation. The aggregation of He bubbles was observed at grain/phase boundaries near the damage peak region. He bubbles were mainly distributed in the α-Al 2 O 3 grains, with only a few in the t-ZrO 2 grains. Although no significant presence of He bubbles was discovered in the ZrC grains. the defects clusters mixed "black dot" defects, dislocation loops were observed. The nanoindentation hardness increased with the irradiation fluences up to 1.0 × 1017 ions/cm2, but decreased at a fluence of 2.0 × 1017 ions/cm2. In the peak damage region, He bubble bands were formed in some α-Al 2 O 3 and t-ZrO 2 grains at the fluence of 2.0 × 1017 ions/cm2. The bubble bands are responsible for the weakened irradiation hardening effect. [ABSTRACT FROM AUTHOR]