In situ synchrotron tomography estimation of toughening effect by semi-ductile fibre reinforcement in a tungsten-fibre-reinforced tungsten composite system

Tungsten-fibre-reinforced tungsten composites (Wf/W) are supposed to enable enhanced toughness owing to extrinsic energy dissipation mechanisms such as interface debonding and plastic deformation of fibre. In particular, the latter is an effective source of toughening, since ductile tungsten fibres can absorb a considerable amount of plastic work. For a precise evaluation of the toughening capability, the energy dissipation mechanisms need to be analysed in detail. To this end, single-fibre tungsten composite specimens are fabricated and the stress-strain behaviour of the tungsten fibre bridging a matrix crack is measured by means of in situ high-energy synchrotron microtomography during a uniaxial tensile test. Despite the high X-ray attenuation in tungsten, a sufficiently high resolution is achieved and clear images of crack extension and deformation are obtained. The amount of absorbed energy due to plastic deformation of the tungsten fibre is determined and compared with values obtained conventionally from single-fibre tensile tests.