Study on the annealing and three-point bending fracture behavior of single W fiber-reinforced W composites with multiple interfaces prepared by CVD

The inherent brittleness of tungsten severely limits its application as plasma-facing materials (PFMs). Tungsten fiber (W_f) reinforced tungsten (W) composites (W_f/W) offer a promising toughening approach for tungsten. However, this toughening method faces significant challenges, such as how to optimize the interface strength and preventing damage to the fiber-reinforced structure. In this study, four types of interfaces (Y, Cr, Y₂O₃, and YSZ) were prepared using magnetron sputtering technology, followed by the fabrication of single W_f-reinforced W composites via chemical vapor deposition (CVD). The fracture behavior of the W_f/W composite before and after the annealing process was investigated through three-point bending tests. The results indicate that the interfaces including yttrium (Y), yttrium oxide (Y₂O₃), and yttria-stabilized zirconia (YSZ) all exhibit weak binding strength, leading to interface debonding during the three-point bending test and resulting in ductile fracture behavior for the composite. In contrast, the chromium (Cr) interface displays a high binding strength and lead to brittle fracture behavior for the composite. After annealing at 1000 °C, the binding strength of Y₂O₃ and YSZ interfaces increases, which causes the brittle fracture behavior of the composite. After annealing at 1600 °C, the Cr interface diffused into the W_f and caused the recrystallization of the W_f. The Y interface underwent melting and solidification, leading to a decrease of the binding strength. The interface strength ranks as follows: Cr > YSZ > Y₂O₃ > Y.