Role of grain size and grain boundaries on irradiation defect production in nanocrystalline SiC

Narasimhan Swaminathan, Izabela Szlufarska, and Dane Morgan

Department of Materials Science and Engineering

Cubic silicon carbide (3C-SiC), known for its excellent mechanical properties and low neutron cross section, is being considered as a prospective structural material for nuclear fission and fusion reactors. Additional improvements in SiC mechanical properties may be possible through use of nanocrystalline (nc) SiC. It is also believed that grain boundaries (gb) can act as sinks for point defects created during primary radiation damage, suggesting that shrinking grain size may enhance the material’s radiation resistance.

Figure: A snapshot of a 4KeV Si PKA induced cascade progressing between two 10nm sized grains in 3C-SiC.

The aim of this research is to better understand the connection between radiation damage and nc structure. For this purpose, point defect production in nanocrystalline (nc) SiC will be studied for various grain sizes and PKA (Primary Knock on Atom) energies using molecular dynamic simulations. Comparing the defects produced during a cascade in the nc with that produced in a single crystal will thus provide a qualitative understanding on the role of grain size and grain boundaries during primary damage cascades in 3C-SiC.