The mechanical properties of reduced activation ferritic/martensitic steels (RAFMs) such as creep, thermal aging, and irradiation resistance are improved by the formation of MX and M₂₃C₆ particles. However, it is well known that these particles are unstable under irradiation. The purpose of the present study is to clarify the details of the radiation-induced amorphization (RIA) of M₂₃C₆ in F82H steels. The instability behavior of M₂₃C₆ under a wide range of irradiation temperatures from R.T. to 773 K and various ion beam energies (2.8, 3.7, 6.4 and 10.5 MeV) was systematically investigated. Two types of materials, F82H and its model alloy (F8), were utilized in this study. TEM observation and selected area electron diffraction analysis before and after irradiation were conducted to evaluate the occurrence of RIA, and the chemical composition was analyzed to reveal the possible relation between atom displacement/diffusion and RIA. In the case of the iron irradiation at the temperature below 598 K, a bilayer contrast of the particle, consisting of an amorphous-rim phase and inner crystalline core, was observed. Similar particle survived in the irradiated F82H at the temperature of 623 K, the RIA was not observed in the F8 specimen. Consequently, the critical temperature of RIA was estimated as 623–673 K. Since the melting temperature (T_m) of M₂₃C₆ is approximately 2173 K, the critical temperature corresponds to ∼0.29 T_m. From the STEM-EDS analysis, the Fe/Cr ratio of the particle decreased with increasing irradiation temperature in the range of 573–623 K. This behavior was qualitatively explained by the formation of the amorphous phase. It is clarified that the occurrence of the RIA of M₂₃C₆ particle can be evaluated by the variation of Fe/Cr ratio.

通过形成MX和M ₂₃ C ₆颗粒，可以降低还原活化铁素体/马氏体钢（RAFM）的机械性能，例如蠕变，热时效和耐辐照性。然而，众所周知这些颗粒在辐射下是不稳定的。本研究的目的是阐明F82H钢中M ₂₃ C ₆的辐射诱导非晶化（RIA）的细节。M ₂₃ C ₆的不稳定性行为系统地研究了在从室温到773 K的宽广照射温度下的各种离子束能量（2.8、3.7、6.4和10.5 MeV）。这项研究使用了两种类型的材料，即F82H及其模型合金（F8）。进行了TEM观察和辐照前后的选定区域电子衍射分析，以评估RIA的发生，并分析化学成分以揭示原子位移/扩散与RIA之间的可能关系。在低于598 K的温度下进行铁辐射的情况下，观察到了由非晶边缘相和内部晶核组成的颗粒的双层对比。相似的颗粒在623 K的温度下在F82H辐照下幸存，在F8标本中未观察到RIA。所以，M ₂₃ C _6的T _m）约为2173 K，临界温度约为0.29 T _m。根据STEM-EDS分析，在573-623 K范围内，随着辐射温度的升高，颗粒的Fe / Cr比值降低。定性解释了非晶态的形成。明确了可以通过Fe / Cr比的变化来评价M ₂₃ C ₆粒子的RIA的发生。