Analysis of recovery process of low-dose neutron irradiation-induced defects in silicon nitride-based ceramics by thermal annealing
Analysis of recovery process of low-dose neutron irradiation-induced defects in silicon nitride-based ceramics by thermal annealing
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DOI：
10.1016/j.jnucmat.2014.07.066
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发表时间：
2014-12
影响因子：
3.1
通讯作者：
Areerak Rueanngoen;K. Kanazawa;M. Imai;Katsumi Yoshida;T. Yano
中科院分区：
文献类型：
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作者：
Areerak Rueanngoen;K. Kanazawa;M. Imai;Katsumi Yoshida;T. Yano
在563K下，对两种不同晶型的氮化硅陶瓷进行了高达8.5×1024N/m2(E>；~0.1 MeV)的中子辐照，并与已报道的SiAlON晶型在相同辐照条件下的退火行为进行了比较。α-和β-Si3N4以及α-和β-SiAlON的宏观长度变化分别为0.11%、0.06%、0.12%和0.14%。根据溶胀数据和显微结构观察，认为低剂量中子辐照氮化硅基陶瓷中的缺陷主要是点缺陷。为了研究缺陷恢复的动力学，对辐照后的样品进行了连续等温退火至1473K，宏观长度变化随退火温度的升高而逐渐减小。α-Si3N4和α-SiAlON的等时退火回复曲线相似，β-Si3N4和β-SiAlON的等时退火回复曲线也相似。复合速率常数为一级反应，随等温退火温度升高而增大。在辐照温度和1473℃之间考虑了两个阶段的恢复过程。在较高温度下，Si3N4和SiAlON的激活能几乎是较低温度下的两倍。在较低的温度范围内，恢复应该通过近距离的Frenkel对的湮灭来发生。另一方面，在较高的温度下，恢复过程可能由分离的Frenkel对的湮灭所支配。此外，Si3N4的缺陷恢复激活能大于SiAlON的缺陷恢复激活能。α-和β-相在两种晶体中的恢复特征不同，这可能是由于晶体结构的不同所致。
Two kinds of silicon nitride ceramics consisting of different polymorphs were neutron-irradiated up to 8.5 × 1024n/m2(E> 0.1 MeV) at 563 K, and their annealing behaviors were compared to those of previously reported SiAlON polymorphs subjected to the same irradiation condition. The macroscopic length change of α- and β-Si3N4and α- and β-SiAlON were 0.11%, 0.06%, 0.12% and 0.14%, respectively. Based on swelling data and microstructural observations, the low dose neutron irradiation-induced defects in silicon nitride-based ceramics were considered to be primarily point defects. In order to investigate the kinetics of defect recovery, these irradiated specimens were isothermally and isochronally annealed continuously up to 1473 K. Macroscopic length change decreased gradually with increasing annealing temperature. Recovery curves of isochronal annealing of α-Si3N4and α-SiAlON were similar, and those of β-Si3N4and β-SiAlON were also similar. The recombination rate constant as a first-order reaction increased with the increasing of the isothermal annealing temperature. A two-stage recovery process was considered between the irradiation temperature and 1473 K. The activation energies at higher temperatures were almost double those at lower temperatures in both Si3N4and SiAlON. At lower temperatures range the recovery should occur by annihilation of close-spaced Frenkel pairs. On the other hand, at higher temperatures, the recovery process may be governed by the annihilation of separated Frenkel pairs. In addition, the activation energies for defect recovery in Si3N4were larger than defects in SiAlON. Recovery characteristics of α- and β-phases were different in both crystals that are suggested to be due to differences in crystal structures.