A novel trench fibre push-out method to evaluate interfacial failure in long fibre composites

R. M. G. De Meyere; K. Song; L. Gale; S. Harris; I. M. Edmonds; T. J. Marrow; E. Saiz; F. Giuliani; D. E. J. Armstrong; O. Gavaldà-Diaz

Journal of Materials Research 36 (2021) 2305-2314

Traditional fibre push-outs for the evaluation of interfacial properties in long fibre ceramic matrix composites present their limitations—solutions for which are addressed in this work by introducing the novel trench push-out test. The trench push-out makes use of a FIB milling system and an SEM in-situ nanoindenter to probe a fibre pushed into a trench underneath, allowing in-situ observations to be directly correlated with micromechanical events. SiCf/BN/SiC composites—candidate material for turbine engines—were used as model materials in this work. Different fibre types (Hi-Nicalon and Tyranno type SA3) were coated with BN interphases, presenting mean interfacial shear stresses of 14 ± 7 MPa and 20 ± 2 MPa, respectively, during fibre sliding. The micromechanical technique enabled visualisation of how defects in the interphase (voids, inclusions & milled notches) or in the fibre (surface asperities, non-uniform coatings) affected the variability of interfacial property measurement. Graphic abstract: [Figure not available: see fulltext.]

DOI: https://doi.org/10.1557/s43578-021-00153-1