Recent progress in research on bonding technologies of W/Cu monoblocks as the divertor for nuclear fusion reactors

Divertor components with excellent comprehensive performance are a new research focus for nuclear fusion reactors. However, the excessive mismatch in the coefficient of thermal expansion (CTE) between W and Cu poses a challenge for their application in the divertor. This paper provides a review of the recent progress in the bonding technologies of W/Cu monoblocks, where the W/Cu monoblock refers to any monoblock assembly with a direct W to Cu interface. The bonding technologies of W/Cu monoblocks with bonding interface materials (brazing and diffusion bonding) and W/Cu monoblocks with bonding interface structures (surface nanosizing technologies of W, coating, and explosive welding) are described in detail. The advantages and limitations of each technology are commented upon. Furthermore, the preparation of W/Cu monoblocks with a W-Cu gradient interlayer and W-Cu functionally graded materials (W-Cu FGMs) with full composition distribution is reviewed. These approaches aim to improve the performance of the W/Cu monoblocks. The mechanical, high heat flux (HHF) resistance, and irradiation resistance performance of the W/Cu monoblocks are summarized and evaluated. These performances are crucial for the successful application of W/Cu monoblocks in the divertor. Finally, based on the comprehensive review, future developments and potential research challenges for W/Cu monoblocks are proposed. This provides insights into the direction of future research in this field.