In situ TEM annealing of ion-amorphized Hi Nicalon S and Tyranno SA3 SiC fibers

In this work, recrystallization of ion-amorphized Hi Nicalon Type S and Tyranno SA3 SiC fibers (4 MeV Au3+, 2 × 1015 cm−2) has been studied via in situ TEM annealing. Both fibers show a two-step recovery process of the radiation damage. First recovery stage starts at temperatures as low as 250 °C and implies recovery of the radiation swelling. Eventually the amorphous layer recrystallizes with no signs of polytype change (3C-SiC). Recrystallization temperatures yield 900-920 °C and 930 °C for the HNS and the TSA3 respectively. HNS fiber shows columnar recrystallization perpendicular to the amorphous-crystalline interphase with a grain growth rate of ∼20 nm min−1. On the other hand, recrystallization of TSA3 fiber is rather “spontaneous” with no preferential growth direction. The different recrystallization is attributed to the different microstructure of the fibers.