Unusual ablation behaviors of tungsten graded network reinforced copper composites synthesized by 3D printing and infiltration sintering at ultra-high temperatures

Tungsten network reinforced functionally graded copper composites were prepared using an integrated 3D printing and infiltration technology to improve high temperature ablation properties of nuclear fusion divertor materials. The composites' ablation behavior was systematically investigated using an argon arc welding torch. Results showed that mass loss of composites was increased firstly but then decreased with the increase of ablation time. During ablation, evaporation of the melted copper reduces the local temperature of tungsten skeleton, whose high melting point also restrict the further evaporation of copper. These mechanisms significantly improve the ablative resistance of CuW gradient composite. Tungsten twinning structures were identified to form during ultra-high temperature (at 6273.15 K) ablation process in a cold environment in air. The formation of distinctive W twinning structures and gradient distribution of copper and tungsten skeleton were identified as the key mechanisms for the significantly enhanced ablation performance of the graded composite.