ABSTRACT

Microstructural changes due to 160 MeV oxygen ion irradiation on pure Nb have been characterised using X-ray Diffraction Line Profile Analyses. Microstructural parameters such as coherent domain size, microstrain within the domain and dislocation density are evaluated from the homogeneously damaged region. It is observed that the domain size decreases along with an increase in microstrain and dislocation density as a function of dose. The local changes in the microstructure have also been evaluated in terms of band contrast, mean angular deviation and local misorientation from electron backscattered diffraction data at the surface and an intermediate depth in the homogenously damaged region of selected irradiated samples and in the unirradiated sample. An increase in mean angular deviation and local misorientation is observed in the highest dose sample, which may be an indication of dislocation loop formation. Defect clusters and dislocation loops are observed using transmission electron microscopy in the highest dose sample. Microhardness measurement has also been carried out on the unirradiated and irradiated samples to correlate the microstructural changes with the mechanical property as a function of dose. It is observed that the hardness of the material increases as a function of dose due to the formation of defect clusters and dislocation loops that pin the movement of dislocations. Finally, a comparison of the microstructures in proton and heavy ion irradiated samples at approximately similar dpa-rate has been carried out to understand the effect of the ion species on the defect morphology.

摘要

由于 160 MeV 氧离子辐射对纯 Nb 的显微结构变化已经使用 X 射线衍射线轮廓分析进行了表征。从均匀损坏的区域评估微观结构参数，例如相干域大小、域内的微应变和位错密度。观察到域尺寸随着微应变和位错密度的增加而减小，作为剂量的函数。微观结构的局部变化也已根据表面电子背散射衍射数据的带对比度、平均角偏差和局部错误取向以及选定辐照样品和未辐照样品的均匀损坏区域的中间深度进行评估。在最高剂量样品中观察到平均角度偏差和局部定向错误的增加，这可能是位错环形成的迹象。在最高剂量样品中使用透射电子显微镜观察缺陷簇和位错环。还对未辐照和辐照样品进行了显微硬度测量，以将显微结构变化与作为剂量函数的机械性能相关联。据观察，由于缺陷簇和位错环的形成导致位错运动，材料的硬度随着剂量的增加而增加。最后，