This paper presents an in situ Transmission Electron Microscopy (TEM) study of the damage formation process in ion-irradiated boron carbide used as neutron absorber for fast nuclear reactors. We focused our experiment on the damage induced by 1 MeV gold ions irradiation performed on the JANNuS-Orsay in situ dual ion beam TEM facility. The effects of the crystallographic orientation and the temperature (RT, 500 °C and 800 °C) on the ion-irradiated boron carbide structure were studied. The different steps of damage formation leading to amorphization are described. At RT, material amorphization is observed at a damage dose threshold around 7.5 displacements per atom (dpa). It is also shown that no amorphization occurred when irradiation is performed at 500 °C or 800 °C up to the highest fluence studied (3 × 10¹⁵ ions cm⁻², i.e. 7.6 dpa).

本文介绍了一种用于快速核反应堆中子吸收剂的离子辐照碳化硼损伤形成过程的原位透射电子显微镜（TEM）研究。我们将实验重点放在在JANNuS-Orsay上原位进行1 MeV金离子辐照引起的损伤双离子束TEM设施。研究了晶体取向和温度（RT，500°C和800°C）对离子辐照碳化硼结构的影响。描述了导致非晶化的损伤形成的不同步骤。在室温下，在约7.5个位移/原子（dpa）的损伤剂量阈值处观察到材料非晶化。还显示出，当在500℃或800℃下进行辐照直至所研究的最高通量（3×10 ¹⁵离子cm ^-2，即7.6 dpa）时，未发生非晶化。