The damage evolution and fracture behavior in the bulk of C/SiC material under monotonic tensile loading have been investigated with the 3D in-situ observations by using X-ray CT. Crack initiated inside the matrix within 0.02 mm below surface when the load was only 19% of the failure strength, and propagated to the surface of matrix and towards the interior of specimen by breaking fibers and matrix when the load was above the elastic limit. With the further increasing of loading, other fiber breaks, matrix breaks and delaminations were observed to initiate and propagate both on the surface and in the bulk of specimen, while the cracks nucleating in the bulk of specimen are generally located at the laminae with a high volume fraction of pores. With the further propagations of cracks, the specimen split in the laminae with a large quantity of pores, while the fiber drawings results in the final fracture in the laminae without a large quantity of pores. The novel method being proposed to characterize the distribution of pores in this paper highlights the relation between the distribution of pores in the bulk of the studied material and cracks initiations and final fracture.

通过X射线CT的3D原位观察，研究了单调拉伸载荷下C / SiC材料整体的损伤演化和断裂行为。当载荷仅是破坏强度的19％时，裂纹会在基体内部低于表面0.02 mm的范围内破裂，当载荷超过弹性极限时，断裂会破坏纤维和基体，从而扩展至基体表面并向试样内部扩展。随着载荷的进一步增加，观察到其他纤维断裂，基体断裂和分层均在试样的表面和整个块体中引发和传播，而在大部分试样中成核的裂纹通常位于具有较高高度的薄片上。毛孔的体积分数。随着裂纹的进一步传播，标本在层状结构中分裂，并形成大量孔隙，而纤维拉伸会导致层状结构最终破裂而没有大量的孔。本文提出的表征孔隙分布的新方法突出了研究材料中孔隙分布与裂纹萌生和最终断裂之间的关系。