The surface topography and microstructure of self-sintered nanopore graphite by Xe ions irradiation

Abstract

Nanopore graphite prepared by self-sintered pitch coke for molten salt reactor was irradiated by 7 MeV Xe26+ to study the irradiation behaviors. The hardness and Young's modulus of self-sintered nanopore graphite (SSNG) were increased due to an increase in defects and close of micro-gap. The SSNG surface remained intact after irradiation. The pore and the gap between the filler particles of SSNG shrink due to the expansion of the filler particles. The microstructure evolution characterization of SSNG samples by the grazing incidence X-ray diffraction showed the increase in interlayer spacing and the expansion of crystallite size along c-axis, which caused the expansion of the filler particles. The defect density increase is the main reason for mechanical properties changes. The high-resolution transmission electron microscopy provides clear and visual evidence for this and showed the evolution of dislocation and interstitial loop. The microstructure evolution characterization of the SSNG is at the atomic scale after irradiation at different depths. The evolution of irradiation-induced defects in SSNG causes the change of microscopic morphology, and the evolution of morphology and defects plays an important role in the change of mechanical properties.