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首页> 外文期刊>Materials at High Temperatures >Oxide microstructure and deuterium ingress in Zr-2.5 Nb CANDU~R pressure tubes
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Oxide microstructure and deuterium ingress in Zr-2.5 Nb CANDU~R pressure tubes

机译：Zr-2.5 Nb CANDU〜R压力管中氧化物的微观结构和氘的进入

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The microstructures of oxides grown on the inside surface (water side) of Zr 2.5 Nb pressure tubes removed from CANDU~R* reactors were characterised by TEM and correlated with deuterium ingress Oxide cross-sections consisted of two structurally distinct regions: a columnar oxide region next to the metal/oxide interface, and an outer coarse equiaxed oxide region Near the metal/oxide interface, the microstructure consisted of columnar grains without overt porosity. Away from the interface, the oxide consisted of coarsened equiaxed grains with (100)_m twins, grain-boundary cracks and nanopores. The oxide microstructures on various pressure tubes differ in the proportion of equiaxed grains. Electron micrographs suggest that a larger proportion of equiaxed grains is associated with higher deuterium uptake. The predominance of grain-boundary cracks n more permeable to water than columnar oxides. Energy dispersive X-ray analyses revealed substantial amounts of Fe-K_(alpha) (and Mn-K_(alpha)) in the equiaxed oxide grains at the outermost surface. Energy Dispersive X-ray mapping of Fe-K_(alpha) and detection of the Mn-K_(alpha) (produced by neutron activation of ~(54)Fe and subsequent decay of ~(54)Fe) in the absence of external excitation, unequivocally demonstrated that the iron had accumulated in the oxide during reactor operation. The Fe concentration was highest near the outermost region, and decreased inwards towards the metal/oxide interface. These results are consistent with permeable equiaxed oxides picking up considerable amounts of Fe at the outermost region from the heavy water coolant.
机译：用TEM表征从CANDU〜R *反应堆中取出的Zr 2.5 Nb压力管内表面（水侧）上生长的氧化物的微观结构，并与氘进入相关。氧化物横截面由两个结构上不同的区域组成：柱状氧化物区域紧挨着金属/氧化物界面，以及靠近金属/氧化物界面的外部粗等轴氧化物区域，其微观结构由没有明显孔隙的柱状晶粒组成。远离界面的氧化物由具有（100）_m孪晶的粗化等轴晶粒，晶界裂纹和纳米孔组成。各种压力管上的氧化物微结构的等轴晶比例不同。电子显微照片表明，等轴晶粒的较大比例与较高的氘吸收有关。晶界裂纹的主要部分比柱状氧化物更能渗透水。能量色散X射线分析表明，在最外表面的等轴氧化物晶粒中存在大量的Fe-K_α（和Mn-K_α）。 Fe-K_α的能量色散X射线映射和Mn-K_α的检测（由〜（54）Fe的中子活化和随后〜（54）Fe的衰变产生）明确地表明，铁在反应堆运行期间已经聚集在氧化物中。铁的浓度在最外层区域附近最高，并向金属/氧化物界面向内降低。这些结果与可渗透的等轴氧化物在重水冷却剂的最外层区域吸收大量的铁相一致。

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