Fabrication and Plasma Exposure of Fine-Grained Tungsten/Copper Functionally Graded Materials in the HT-7 Tokamak

Five-layered W/Cu functionally graded materials with fine grain sizes of 0.2, 1, and 7 m were fabricated by resistance sintering under ultrahigh pressure. Microstructure analysis found that they have a good graded composition distribution and mechanical properties. After about 2000 s edge plasma exposure in the HT-7 superconducting tokamak, the results indicated that the fine-grained tungsten can enhance mechanical strength, and it is favorable to hold back crack propagation and growth; however, the effects on impurity deposition and compound formation were not obvious.