Large-Scale Tungsten Fibre-Reinforced Tungsten and Its Mechanical Properties

Tungsten-fibre-reinforced tungsten composites ((Formula presented.)) have been in development to overcome the inherent brittleness of tungsten as one of the most promising candidates for the first wall and divertor armour material in a future fusion power plant. As the development of (Formula presented.) continues, the fracture toughness of the composite is one of the main design drivers. In this contribution, the efforts on size upscaling of (Formula presented.) based on Chemical Vapour Deposition (CVD) are shown together with fracture mechanical tests of two different size samples of (Formula presented.) produced by CVD. Three-point bending tests according to American Society for Testing and Materials (ASTM) Norm E399 for brittle materials were used to obtain a first estimation of the toughness. A provisional fracture toughness value of up to (Formula presented.) was calculated for the as-fabricated material. As the material does not show a brittle fracture in the as-fabricated state, the J-Integral approach based on the ASTM E1820 was additionally applied. A maximum value of the J-integral of (Formula presented.) ((Formula presented.)) was determined for the largest samples. Post mortem investigations were employed to detail the active mechanisms and crack propagation.