The understanding of the neutron irradiation effects in tungsten is of significant importance for its use as a plasma facing material in future fusion devices. In this study, cold rolled tungsten is neutron irradiated at the Belgian BR2 fission reactor at the temperatures 600, 800, 900 and 1200 °C to a dose of 0.18 displacements per atom (dpa). The neutron induced changes in the microstructure are investigated as a function of irradiation temperature using transmission electron microscopy, positron annihilation spectroscopy and electrical resistivity measurements. The influence of the irradiation on the elastic properties and the hardness is examined using the impulse excitation techniques and depth-sensing indentation. Voids and dislocation loops are observed at all the irradiation temperatures. As the irradiation temperature increases the number density of both voids and loops decreases whereas their size increases. The total dislocation density increases after irradiation at 600 °C whereas it decreases for higher temperature irradiations. Furthermore, the formation of very small vacancy clusters in the temperature range of 800 - 900 °C is revealed by PAS measurements. A systematic decrease in the values of Young's and shear moduli is observed as the irradiation temperature increases and this decrease is of about 3.5% after irradiation at 1200 °C. A considerable hardening effect is observed at all irradiation temperatures. The hardness increases with irradiation temperature reaching a maximum at 800 °C and remains almost constant at higher irradiation temperatures.

中文翻译：

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中子辐照冷轧钨显微组织的演变及其与硬度的相关性

了解钨的中子辐照效应对于将其用作未来聚变装置中的面向等离子体材料具有重要意义。在这项研究中，冷轧钨在比利时 BR2 裂变反应堆中在 600、800、900 和 1200 °C 的温度下受到中子辐照，剂量为每原子 0.18 位移 (dpa)。使用透射电子显微镜、正电子湮没光谱和电阻率测量研究了中子引起的微观结构变化作为辐照温度的函数。使用脉冲激励技术和深度传感压痕来检查辐照对弹性性能和硬度的影响。在所有辐照温度下均观察到空洞和位错环。随着辐照温度的增加，空隙和环的数量密度减小，而它们的尺寸增加。在 600 °C 辐照后，总位错密度增加，而在更高温度辐照后，总位错密度降低。此外，PAS 测量揭示了在 800 - 900 °C 温度范围内形成非常小的空位簇。随着辐照温度的升高，观察到杨氏模量和剪切模量的值系统性降低，并且在 1200 °C 辐照后，这种降低约为 3.5%。在所有辐照温度下都观察到相当大的硬化效应。硬度随着辐照温度的增加而增加，在 800 °C 时达到最大值，并且在更高的辐照温度下几乎保持恒定。