Nano-to macroscale In Situ observation of microcrack formation in carbon fiber-reinforced plastic under loading using synchrotron transmission X-ray microscopy.

The nanoscale fracture mechanism of carbon fiber-reinforced plastics (CFRPs) is still debated owing to the considerable difficulty in determining the three-dimensional mechanism of fracture using conventional techniques, such as optical and/or electron microscopy, which rely on side-surface-and fracture-surface-based observations. In this study, microcrack formation under loading was characterized at multiple scales and in situ using non-destructive X-ray computed tomography (X-CT) and transmission X-ray microscopy (TXM) measurements—the first such characterization, to the best of our knowledge. The initiation of voids and cracks clearly arises not only from local stresses but also from two competing nanoscale mechanisms of fiber/plastic interface debonding and in-resin crack initiation. The initiation and propagation of cracks at the nanoscale are significantly affected by the geometrical distribution of the local fibers. Nanoscopic synchrotron X-CT measurements with TXM provide information on the three-dimensional nanoscale mechanisms during deformation, which is indispensable for understanding heterogeneous materials such as CFRPs. [ABSTRACT FROM AUTHOR]