The shrinkages presented in sintering process of tungsten alloys are extremely detrimental to their practical applications in fusion reactors. Positively in this work, we effectively reduced the shrinkages via synergistically applying Ti-doping and annealing process on tungsten‑potassium (WK) alloys. This shrinkage-fill effect only works in the one with trace amount of titanium doping, such as 0.05 wt%Ti or 0.5 wt%Ti. Due to such effect, the compressive strength was improved by ~18%. Based on morphological and elementary analyses, we speculated that the Ti-rich particles along the grain boundaries of WK alloys were activated and migrated into shrinkages during annealing. Further Ti doping (e.g. 1wt.%Ti) led to nanoscale grain refinement in WK alloys, which almost doubled the compressive strength. In this case, an unconventional grain-refinement model was proposed. Furthermore, anomalous grain growth was observed in WK-3wt.%Ti, which was attributed to the formation of Ti-rich regions and the corresponding raise of energy in grain boundaries. The fabricating strategies in this work may benefit the design of refractory tungsten alloys with less shrinkages and ultra-fine grains.

钨合金烧结过程中出现的收缩率对其在聚变反应堆中的实际应用极为不利。在这项工作中积极地，我们通过在钨钾（WK）合金上协同应用Ti掺杂和退火工艺有效地减少了收缩。这种收缩填充效果仅适用于痕量的钛掺杂（例如0.05 wt％Ti或0.5 wt％Ti）的情况。由于这种效果，抗压强度提高了约18％。基于形态学和元素分析，我们推测沿WK合金晶界的富Ti颗粒在退火过程中被激活并迁移为收缩。进一步的Ti掺杂（例如1wt。％Ti）导致WK合金中的纳米级晶粒细化，这几乎使抗压强度提高了一倍。在这种情况下，提出了一种非常规的晶粒细化模型。此外，在WK-3wt。％Ti中观察到了异常的晶粒长大，这归因于富钛区的形成和晶界中能量的相应升高。这项工作中的制造策略可能有利于设计收缩率低和超细晶粒的耐火钨合金。