A new nano-mechanics in-situ transmission electron microscope (TEM) experimental apparatus was developed for measuring applied load and indentation depth curve during the in-situ observation in high voltage electron microscope (HVEM). By using this new apparatus, the crack initiation and propagation at the interface between SiC matrix and carbon layer coated on SiC fiber in SiC/SiC composite can be directly observed with measuring the load -displacement curve of a miniaturized double notch shear (DNS) test. The inter-laminar shear strength of NITE (nano-powder infiltration and transient eutectic process) SiC/SiC composite was estimated as 2.8 ×10~3 MPa, which is about thirty times higher than the result obtained by the conventional DNS test. From the finite element analysis with the interface element about the miniaturized DNS test, it was revealed that the maximum load can be predicted by assuming the higher yield stress of SiC and the reason of the extremely high shear strength seems to be this higher yield stress due to the lower density and distribution of defects.
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