使用瞬态光栅光谱（TGS），我们测量暴露于不同水平的20 MeV自离子辐照的钨的热扩散率。每原子位移（dpa）低至3.2 x 10^-4的损伤会导致热扩散率显著降低。0.1 dpa及以上的剂量，直至10 dpa，在室温下从原始值降解约55%。使用动力学理论模型，辐射引起的点缺陷的密度估计的基础上测得的变化，作为剂量的函数的热扩散率。这些预测进行了比较，在透射电子显微镜（TEM）中观察到的点缺陷和位错环密度。分子动力学（MD）的预测相结合的TEM观察，以估计与缺陷簇太小，TEM探测的点缺陷的密度。当这些“看不见的”缺陷占，总的点缺陷密度一致，以及从TGS的剂量范围跨越3个数量级的估计。动力学理论模型也被用来估计预期由于TEM可见和不可见的缺陷的热扩散率退化。精细分布的不可见的缺陷似乎发挥更重要的作用，在热扩散率降低比较大的TEM可见位错环。这项工作证明了TGS的能力，结合动力学理论模型，提供快速，定量的洞察缺陷密度和辐照材料的性能演变。
英文摘要：
Using transient grating spectroscopy (TGS) we measure the thermal diffusivity of tungsten exposed to different levels of 20 MeV self-ion irradiation. Damage as low as 3.2 x 10^-4 displacements per atom (dpa) causes a measurable reduction in thermal diffusivity. Doses of 0.1 dpa and above, up to 10 dpa, give a degradation of around 55% from the pristine value at room temperature. Using a kinetic theory model, the density of irradiation-induced point defects is estimated based on the measured changes in thermal diffusivity as a function of dose. These predictions are compared with point defect and dislocation loop densities observed in transmission electron microscopy (TEM). Molecular dynamics (MD) predictions are combined with the TEM observations to estimate the density of point defects associated with defect clusters too small to be probed by TEM. When these "invisible" defects are accounted for, the total point defect density agrees well with that estimated from TGS for a range of doses spanning 3 orders of magnitude. Kinetic theory modelling is also used to estimate the thermal diffusivity degradation expected due to TEM-visible and invisible defects. Finely distributed invisible defects appear to play a much more important role in the thermal diffusivity reduction than larger TEM-visible dislocation loops. This work demonstrates the capability of TGS, in conjunction with kinetic theory models, to provide rapid, quantitative insight into defect densities and property evolution in irradiated materials.
Lattice swelling and modulus change in a helium-implanted tungsten alloy: X-ray micro-diffraction, surface acoustic wave measurements, and multiscale modelling
