In situ TEM investigations of the microstructural changes and radiation tolerance in SiC nanowhiskers irradiated with He ions at high temperatures
In situ TEM investigations of the microstructural changes and radiation tolerance in SiC nanowhiskers irradiated with He ions at high temperatures
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原位 TEM 研究高温 He 离子辐照 SiC 纳米晶须的微观结构变化和辐射耐受性
DOI：
10.1016/j.actamat.2021.116820
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发表时间：
2021
期刊：
影响因子：
9.4
通讯作者：
Aradi E
中科院分区：
文献类型：
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作者：
Aradi E
利用离子辐照原位透射电子显微镜（TEM）研究了碳化硅纳米晶须（SiC NW）的微观结构变化，并将其作为纳米多孔SiC的模型体系。使用6 keV He离子在500 °C和1000°C之间的温度和高达20 dpa的剂量下进行辐照。这些结果进行了比较，在相同的条件下，在SiC薄箔的辐射效应，以建立其响应辐射损伤的差异。辐照温度在不同微观结构的演变中起着重要作用;在500°C下，在纳米线中观察到小的缺陷簇，以及使用能量过滤TEM（EFTEM）绘制的纳米线表面处的碳偏析。在800°C下，在NW基质中观察到小的He气泡（直径2-4 nm），而在箔中形成He片晶和气泡盘。在1000°C下，在NW中观察到几种变化，包括孪晶边界处的气泡、空隙和富氧沉淀物。大的表面积与体积比增强了缺陷复合，抑制了SiC纳米线中的缺陷密度，与表明高辐射耐受性的箔相比;然而，元素偏析和沉淀可能限制其在先进核反应堆中的应用。
Using in-situ transmission electron microscopy (TEM) with ion irradiation, we investigated the microstructural changes in silicon carbide nanowhiskers (SiC NWs) which were used as a model system for nanoporous SiC. Irradiations were carried out using 6 keV He ions at temperatures between 500 and 1000°C and doses up to 20 dpa. These results are compared with the irradiation effects in SiC thin foils under the same conditions to establish differences in their response to radiation damage. The irradiation temperature played a significant role in the evolution of different microstructures; at 500°C, small defect clusters were observed in the NWs together with a segregation of carbon at the surface of the NWs mapped using energy-filtered TEM (EFTEM). At 800°C, small He bubbles (2–4 nm in diameter) were observed in the NW matrix while He platelets and bubble discs formed in the foils. At 1000°C, several changes were observed in the NWs including bubbles at twin boundaries, voids and oxygen-rich precipitates. The large surface area to volume ratio enhances defect recombination supressing the defect density in the SiC NWs compared to the foils indicating high radiation tolerance; however, elemental segregation and precipitation may limit its application in advanced nuclear reactors.