3D analysis of cracking behaviour under indentation in ion-irradiated beta-SiC.

To provide a microstructural basis for evaluating fracture toughness by an indentation test, a new method to analyse three-dimensional (3D) cracking behaviour in beta-SiC is developed. As an example, the effect of ion irradiation on crack propagation was studied. The sequential cutting-out of thinned sections by focused ion beam (FIB) processing around an indentation impression enabled the reconstruction of the 3D behaviour of cracking near the indentation impression. The FIB processing has an advantage in making finely polished thin sections for scanning electron microscopy (SEM)/transmission electron microscopy without damaging the structure near cracks. In the present work, the procedure of cross-sectioning and the results of crack propagation analysis in beta-SiC by SEM inspection are described.

Microstructural analysis of the deformation range under nano-indentation in beta-SiC.

As a powerful tool to analyse microstructural evolution under irradiation and the interaction of moving dislocations with radiation-induced defects, a focused ion beam (FIB) method was applied to ion-irradiated SiC followed by the nano-indentation test. An FIB method has excellent capability to prepare thin foils from the area of interest with a high accuracy of location and wide flexibility in the sampling direction. These advantages are demonstrated in the application to Si ion-irradiated SiC by transmission electron microscope observation.