In situ imaging of Ceramic Matrix Composite interphase failure

Fibre reinforced ceramic matrix composites (CMCs) are being investigated as a means of achieving excellent thermomechanical properties at high temperatures for structural applications but with much higher toughness than conventional ceramics. High fracture toughness relies upon energy dissipation during crack propagation and the BN interphase between the SiC fibre and the SiBCN matrix plays a key role. Here we will use fast in situ X-ray tomography on ID19 to reveal the role of the interphase during failure under 3 point-bending and compact tension with the necessary high speed and spatial resolution (2 tomos per second and 1 μm voxel resolution) to quantify the energy absorbing fibre-pull-out mechanisms for the first time. This will enable us to shine new light on the composite design by calculating the energy absorption as a function of interphase strength for the first time as damage progresses.