Microstructural evolution of helium-irradiated 6H-SiC subjected to different irradiation conditions and annealing temperatures: A multiple characterization study
Microstructural evolution of helium-irradiated 6H-SiC subjected to different irradiation conditions and annealing temperatures: A multiple characterization study
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不同辐照条件和退火温度下氦辐照 6H-SiC 的微观结构演变：多重表征研究
DOI：
10.1016/j.actamat.2019.09.027
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发表时间：
2019-12-01
期刊：
影响因子：
9.4
通讯作者：
Polcar, T.
中科院分区：
文献类型：
--
作者：
Daghbouj, N.;Li, B. S.;Polcar, T.
研究了6 H-SiC在不同辐照条件和退火温度下的微观结构现象，以评估6 H-SiC作为核结构材料的适用性。为此目的，6 H-SiC的单晶在300 keV下以不同的能量密度和在25至750 ℃的温度范围内经受He+辐照。卢瑟福背散射/沟道（RBS/C），X射线衍射（XRD）和透射电子显微镜（TEM）分析相结合，揭示了由辐照和随后的退火（750至1500摄氏度）引起的微观结构变化。在室温下，在2.5 × 10（16）cm（-2）（0.66 dpa）的能量密度下开始发生非晶化。相反，在高辐照温度和能量密度下，非晶化被阻止。此外，形成了位于最大He浓度（Rp）周围的薄且高度应变的区域。该区域是由于间隙原子的积累，间隙原子在应变梯度和高温的作用下被推向高度损伤区域。无论能量密度和辐照温度如何，材料都存储弹性能量，这导致He在不同的缺陷几何形状中被捕获。对于低于750摄氏度的照射温度，氦在退火后变粗的气泡中积累。另一方面，对于750摄氏度的辐照温度，氦被捕获在血小板中（即使是中等通量），在退火过程中演变成均匀致密的空腔阵列。DFT计算表明，气泡处于高压下，有助于发展单晶6 H-SiC中的整体拉伸应变。(C)2019 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
The microstructural phenomena occurring in 6H-SiC subjected to different irradiation conditions and annealing temperatures were investigated to assess the suitability of 6H-SiC as a structural material for nuclear applications. To this aim, a single crystal of 6H-SiC was subjected to He+ irradiation at 300 keV with different fluences and at temperatures ranging from 25 to 750 degrees C. Rutherford backscattering/channeling (RBS/C), X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses were combined to shed light on the microstructural changes induced by irradiation and subsequent annealing (750 to 1500 degrees C). At room temperature, amorphization starts to occur at a fluence of 2.5 x 10(16) cm(-2) (0.66 dpa). On the contrary, amorphization was prevented at high irradiation temperatures and fluences. Furthermore, a thin and highly strained region located around the maximum He concentration (Rp) formed. This region results from the accumulation of interstitial atoms which are driven toward the highly damaged region under the actions of a strain gradient and high temperature. Regardless of the fluence and irradiation temperature, the material stores elastic energy, which leads to the trapping of He in dissimilar defect geometries. For irradiation temperatures below 750 degrees C, helium was accumulated in bubbles which coarsened after annealing. On the other hand, for an irradiation temperature of 750 degrees C, helium was trapped in platelets (even for medium fluence), which evolved into a homogeneous dense array of cavities during annealing. DFT calculations show that the bubbles are under high pressure and contribute to developing the overall tensile strain in the single crystal 6H-SiC. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.