Evidence for cascade overlap and grain boundary enhanced amorphization in silicon carbide irradiated with Kr ions

Evolution of amorphous domains in silicon carbide with 1 MeV Kr²⁺ irradiation is investigated using high-resolution transmission electron microscopy and simulations. An unusual morphology of highly curved crystalline/amorphous boundaries is observed in the images, which is identified as a result of cascade overlap and reproduced by a coarse-grained model informed by atomistic simulations. Comparison of local amorphization fractions near grain boundaries and within grain interiors provides experimental evidence for the interstitial starvation mechanism in SiC for the first time. As a competing effect to defect sinks, interstitial starvation increases the rate of local amorphization near grain boundaries and reduces the radiation resistance of nanocrystalline silicon carbide.