The effect of Y2O3 particles on the microstructure and mechanical properties of tungsten fiber-reinforced tungsten composites

Tungsten fiber-reinforced tungsten (W_f/W) composites are a promising plasma-facing material, and the microstructure at the interface between W fibers and the W matrix greatly impacts performance. In this study, a new kind of W_f/W-Y₂O₃ composites was developed with the addition of Y₂O₃ particles to the W matrix in order to modify the interface microstructure between W fibers and the matrix. The microstructure and mechanical properties of these composites were investigated through sintering at temperatures ranging from 1500 °C to 1800 °C. The Y₂O₃ particles with a face-centered cubic crystal structure were formed at the interface between W fibers and the matrix, which is beneficial for weakening the bonding strength. The W_f/W-Y₂O₃ composites exhibited pseudo-plasticity at low sintering temperatures, which show the highest bending strength (261 MPa) and fracture energy (6.66 kJ/m²) at 1600 °C. The grains in W particles become the recrystallized nuclei on the surface of W fiber through the bonding of W powder and W fibers. Then, these recrystallized nuclei grow into W fibers by migration of bonding boundaries. However, the Y₂O₃ particles in the W powder can inhibit the migration of grain boundaries, thereby suppressing the abnormal grain growth behavior at the surface of W fiber.