Effect of potassium doping on the thermal shock behavior of tungsten

• Traditional W–K with different potassium contents were tested under ELM-like high heat load.
• SPS sintered W–K was prepared and its thermal shock performance was comparably studied.
• The damage after thermal shock showed a decreasing tendency as potassium content increase.
• SPS sintered W–K showed better performance than traditional W–K in the thermal shock test.

The effect of potassium doping on the thermal shock behavior of tungsten is investigated in this paper. Traditional W–K samples with different potassium contents were tested by an electron beam at an absorbed power density of 0.37 GW/m2. It shows that the damage after thermal shock test is smaller with potassium content increasing, but the cracking threshold is not improved. It suggests that for traditional W–K sample the potassium bubbles do have some pinning effects on tungsten but not enough to prevent cracking in transient high heat load. The thermal shock behavior of spark plasma sintered W–K (SPS–WK) was comparably studied. In SPS–WK, potassium bubbles not only distribute along the grain boundaries but also retain inside the grains. Size of the potassium bubbles inside the grains is in the range of 20–100 nm. This microstructure leads to higher thermal shock resistance and no obvious damage occurred after transient high heat load at 0.37 GW/m2. This may provide some important information to improve thermal shock resistance for W–K PFM.