SiC single fibre full-fragmentation during straining in a Ti-6Al-4V matrix studied by synchrotron X-rays

High spatial resolution synchrotron X-ray strain measurements and radiography/tomography have been combined to study the progressive fragmentation process during a single fibre full-fragmentation test. In this manner it has been possible to observe the fragmentation sequence and to determine the interfacial shear stress as a function of position along the fibre. The SCS-6 fibre failed after it was elastically strained locally to 1.5%. The interfacial frictional shear strength inferred from the longitudinal strain profile of the broken fibre was calculated to be around 200 MPa, whereas a conventional post mortem full fragmentation analysis based on the mean fragment length would have incorrectly given a value of ~700 MPa. This is due to the degradation of the fibre strength after the initial fibre fracture event. After failure, interface sliding was observed along considerable lengths of the fibre matrix interface. Upon unloading some reverse frictional sliding was found to take place. The morphology of the fibre cracks as well as the occurrence of matrix cracks as the sample approaches saturation fragmentation were also determined from radiographic and tomographic images. © 2002 Acta Materialia Inc. Published by Elsevier Science B.V. All rights reserved.