Abstract:

Background: As one of the most attractive materials for the first wall or structural materials in fusion reactors, silicon carbide (SiC) is subjected to strong heat flux, neutron radiation and the bombardment by energetic ions. However, defects in material will be induced by high temperature and high radiation. Purpose: The analysis of irradiation damage behavior in SiC is important for the development of fusion reactors. Methods: 6H-SiC were irradiated by 100-keV He+ at 600 oC in doses of 5×1015ions?cm?2, 1×1016 ions?cm?2, 3×1016 ions?cm?2 and 8×1016ions?cm?2. Multi-mode scanning probe microscopy techniques, including tapping mode atomic force microscopy (AFM), and nano-indentation/scratch and conduction mode AFM techniques were used to analyze the irradiation damage. Results: He ion irradiation with the dose of 5×1015?1×1016 ions?cm?2 leads to an obvious change of surface topography. It can be clearly seen the surface swelling of irradiated samples. The surface roughness and root mean square roughness (RMS) value increased with increasing He+ doses. However, the nano hardness and scratching resistance decreased with increasing He+ doses. The distributions and morphologies of helium bubble could be clearly observed by conduction AFM. The surface swellings of the irradiated samples were mainly produced by the internal pressure of helium bubbles. Conclusion: We have performed multi-mode scanning probe microscopy techniques for detecting the He+ irradiated SiC samples. This technique can provide a comprehensive evaluation of irradiated fusion materials.

Key words: Silicon carbide (SiC), Irradiation damage, Nano-indentation/scratch, Multi-mode scanning probe microscope