Response to irradiation of nanocrystalline 3CSiC is studied using 2 MeV Au2+ ions at elevated temperatures and is compared to the behavior of its monocrystalline counterpart under the identical irradiation conditions. The irradiated samples are characterized using in-situ ion channeling, ex-situ X-ray diffraction, and helium ion microscopy. Compared to monocrystalline 3CSiC, a faster amorphization process in the nanocrystalline material (average grain size = 3.3 nm) is observed at 500 K. However, the nanograin grows with increasing ion fluence at 550 K and the grain size tends to saturate at high fluences. The striking contrast demonstrates a sharp transition from irradiation-induced interface-driven amorphization at 500 K to crystallization at 550 K. The results could potentially have a positive impact on nuclear fuel cladding and structural components of next-generation nuclear energy systems.