Fabrication and fracture behaviors of the continuous brittle fiber reinforced tungsten composites fabricated via field-assisted sintering technology

Tungsten (W) is a promising candidate material for the plasma-facing components in future fusion reactors. However, it has issues regarding the intrinsic brittleness as well as operational embrittlement. Tungsten fiber reinforced tungsten (Wf/W) composites overcome these issues by using extrinsic toughening mechanisms. Due to neutron irradiation and high-temperature recrystallization during fusion operation, the ductility of the fibers may degrade over a long period of service. Therefore, it is necessary to investigate the fracture behavior of Wf/W composites with brittle fibers. In the present work, the tungsten fibers were embrittled by carbonization. Subsequently, the continuous brittle Wf/W composite with yttrium oxide (Y2O3) interface was fabricated by the field-assisted sintering technology process. The microstructure of the prepared Wf/W composites was characterized. The fracture behavior and toughening mechanisms were discussed in detail based on the experimental results of 3-point bending tests and the corresponding finite element simulation. The composites show a pseudo-ductile fracture behavior. Cracks are hindered and deflected by the de-bonded fiber-matrix interface. The extrinsic toughening mechanisms of interface de-bonding, crack bridging, and fiber pull-out are active. This indicates the reinforcement concept still works even though all components in the Wf/W are brittle.