高温合金中硼化物精细结构的高空间分辨电子显微学研究

Microelement B is widely added into almost all commercial superalloys because B contributes to strengthening grain boundaries at high temperature during service. Generally, B is present in two different forms. Besides the solute state in matrix, B tends to react with transition elements at high temperatures, giving rise to various borides including M ₂ B, M ₃ B ₂ and M ₅ B ₃ phases. An accurate knowledge of the microstructural characterizations of these borides is of great importance for a better understanding of the structure-property relationship and designing materials with improved properties. By means of various advanced techniques based on the aberration-corrected transmission electron microscopy (TEM), microstructural features of above borides have been systematically investigated. Various defect features which were controversial in the past have been clarified. In this paper, after a brief review on the studies of borides, the atomic- scale information on the microstructural features has been presented. Finally, some prospects for future studies have been proposed.