
High-heat-flux performance of monoblock target prepared with advanced W-K plate
Fan Feng, Youyun Lian, Jianbao Wang, Jiupeng Song, Mengxia Liang, Yuzhong Jin, Xiang Liu
Southwestern Institute of Physics, Xihua University
Potassium-doped tungsten (W-K) is a promising plasma-facing material because nanoscale K bubbles may improve microstructural stability without introducing solid second phases. In this work, large-scale rolled W-K plates containing ~90 ppm K were fabricated by powder metallurgy, hot rolling and stress-relief annealing, and were machined into ITER-like water-cooled monoblock mock-ups. The rolled plates showed a tensile strength of 1225 MPa at 50 °C , ductility exceeding 20% at 200 °C, and a recrystallization temperature of ~1500 °C . Transient electron-beam thermal-shock tests on the RD-TD plane demonstrated that the as-rolled and 1400 °C -annealed W-K remained crack-free after 100 pulses of 1 ms up to 0.66 GW/m², whereas specimens annealed at ≥1500 °C exhibited reduced cracking thresholds. Under steady-state high-heat-flux fatigue, W-K monoblocks maintained structural integrity at 20 MW/m² for up to 1500 cycles, although surface roughening, intergranular fissures and local melting developed with increasing cycle number. At 25 MW/m², severe roughening/erosion occurred after 500 cycles as the apparent surface temperature exceeded 2300 °C . A key mechanistic finding is that crack density and crack depth are governed by different factors: crack density increased mainly with accumulated thermal cycles, whereas crack depth was controlled predominantly by peak surface temperature. Stable K-bubble dispersion is suggested to retard grain-boundary migration and suppress microcrack nucleation, contributing to the high thermal-shock and HHF tolerance of rolled W-K monoblocks.



