In-situ matrix and interfacial damage evolution of T-300TM Cf/SiC mini-composites with single/hybrid texture PyC microstructures under tensile loading

PyC interphase plays a crucial role in improving the mechanical properties of Cf/SiC composites. In this paper, the PyC interphase was designed as G1 medium-high texture PyC (MT-HT-PyC) interphase, G2 low and high hybrid texture PyC (LT/HT-PyC) interphase, and G3 low texture PyC (LT-PyC) interphase. The differences of G1 ∼ G3 PyC interphases were characterized using the transmission electron microscope (TEM) and scanning electronic microscope (SEM) technologies. In-situ tensile and μ-CT experiments of T-300TM Cf/SiC composites with the G1 ∼ G3 PyC interphases were conducted to evaluate the evolution of matrix cracking upon initial loading to final fracture. Additionally, the in-situ scanning ion beam etching (SIBE) experiments of Cf/SiC composites with G1 ∼ G3 PyC interphases were also conducted to observe and analyze the evolution of interfacial crack. Experimental results showed that the introduction of LT-PyC phase into the PyC interphase not only efficiently alleviated the thermal residual stress (TRS), but also changed the location of interfacial crack from fiber/interphase (F/I) or interphase/matrix (I/M) interface to the interior of PyC interphase, which significantly improved the load capacity of Cf/SiC composite. New loading carrying mode of carbon fibers in Cf/SiC composite was also proposed and discussed.