Enhanced thermal fatigue resistance of W/Cu divertor components via serrated interface design: experimental and numerical insights

Abstract Divertors constructed primarily from tungsten–copper (W/Cu) composites are essential components in magnetically confined fusion reactors, where they are subjected to extreme thermal loads. However, the W/Cu interface is particularly susceptible to fatigue-induced fracture under high heat flux (HHF) conditions. Modifying the interfacial configuration between tungsten and copper presents a promising approach to enhance the fatigue life of divertors. This study introduces a millimeter-scale serrated W/Cu interfacial design with finite element simulations and compares the fatigue performance of planar and serrated interfaces under cyclic thermal loading, with a focus on their thermomechanical behavior and failure mechanisms. The HHF experiments with digital image correlation and infrared thermography demonstrate that the serrated interface enhances fatigue life by about five times compared to the planar configuration under cyclic loading at 10 MW m −2 . After 1300 thermal cycles, metallographic observations reveal that the planar interface experiences severe shear-driven fracture, while the serrated interface maintains structural integrity with minimal damage. This enhancement in fatigue performance is attributed to the serrated geometry, which redistributes shear strain, concentrates deformation at serration tips, and induces compressive strains that suppress crack propagation. These findings provide the practical and economical optimization of W/Cu interfacial structures, supporting the development of more robust divertors for fusion reactors operating under more extreme thermal environments.