In this work, we have performed neutron irradiation and sub-sequent hardness measurements on a series of tungsten grades to screen the irradiation-induced hardness as a function of irradiation temperature reaching up to 1200 °C. The selected irradiation temperatures were chosen by performing temperature analysis of the expected irradiation temperature on tungsten monoblock during the steady state operation in ITER, where 1200 °C corresponds to the surface temperature at 10 MW/m² flux density expected during normal operational conditions. The applied neutron fluence and flux (using BR2 material test reactor, up to 1 dpa) is representative of ITER irradiation conditions except the neutron spectrum. However, the measures were taken to reduce the thermal neutron flux to limit the transmutation closer to the fusion conditions. The irradiation-induced hardness measured in single crystal after irradiation at 600–800 °C agrees very well with the earlier data reported after HFIR irradiation experiments. The new irradiation data obtained in the temperature range 900–1200 °C show that even at one third melting point the neutron exposure raises the hardness by 40% to 70%, depending on the selected grade. Screening measurements by transmission electron microscopy, applied to clarify the origin of the hardening at 1200 °C, have proven the presence of the dislocation loops and high density of voids. The presence of those defects should imply the reduction of thermal conductivity, fracture toughness as well as alteration of hydrogen isotope permeation and trapping.

在这项工作中，我们对一系列钨等级进行了中子辐照和随后的硬度测量，以筛选辐照引起的硬度与辐照温度达到1200°C的关系。通过在ITER稳态运行期间对钨单体的预期辐照温度进行温度分析来选择选定的辐照温度，其中1200°C对应于10 MW / m ²的表面温度在正常操作条件下预期的磁通密度。施加的中子注量和通量（使用BR2材料测试反应器，最高1 dpa）代表ITER辐照条件，除了中子谱。但是，采取了减少热中子通量的措施，将the变限制为更接近聚变条件。在600–800°C辐照后在单晶中测得的辐照硬度与HFIR辐照实验后报道的早期数据非常吻合。在900-1200°C的温度范围内获得的新辐照数据表明，即使在三分之一的熔点下，中子暴露也会使硬度提高40％至70％，具体取决于所选等级。通过透射电子显微镜对测量结果进行筛选，以阐明在1200°C时硬化的起源，已经证明位错环的存在和高密度的空隙。这些缺陷的存在应暗示导热系数，断裂韧性的降低以及氢同位素渗透和俘获的改变。