The oxidation behavior of bulk ZrSi2 at 700, 1000, and 1200 °C in ambient air has been investigated. Parabolic to cubic oxide layer growth kinetics was confirmed by weight gain measurements and the average oxide layer thickness was 470 nm, 6.7 µm, and 37 µm at 700 °C, 1000 °C, and 1200 °C, respectively, after 5 h oxidation tests. Evolution of compositionally modulated nano/micro structures was confirmed in the oxide layer. At 700 °C, Si diffusion resulted in discontinuous Si-rich oxide phases in amorphous Zr–Si–O matrix. At 1000 °C, complex multilayered structures such as fine and coarse irregular spinodal structures, wavy Si-rich oxide, and Si-rich islands evolved. At 1200 °C, additional nucleation of nanoscale ZrO2 particulate phase was observed. The spinodal structures were confirmed to be crystalline ZrO2 and amorphous SiO2, and the thermodynamic driving force for phase evolution has been explained by extension of liquid miscibility gap in the binary ZrO2–SiO2 phase diagram.

The grain size dependence of the radiation response of silicon carbide (SiC) has been studied under 1.0 MeV Kr2+ ion irradiation. It was found that radiation resistance decreased with grain refinement, in contrast to previous studies on the same nanocrystalline (nc) SiC material using Si ion and high voltage electron irradiation. The effect of grain size on radiation response may depend upon the ion species used due to a potential change in amorphization mechanism. It was also determined that temperature had a strong effect on the grain size dependence of the radiation response in SiC due to the activation temperatures of critical recombination and migration reactions. This work explores the possible impacts of irradiation species, temperature, and experimental design on the radiation response of SiC.