The micro-mechanism of rhenium promoting the formation of stacking faults in the Ni-based model single crystal superalloys

摘要

It is important and necessary to understand the micro-mechanism of rhenium (Re) effect in the deformation process. The in-situ tensile experiments of Ni-Al and Ni-Al-Re model single crystal superalloys have been carried out in scanning electron microscope at 750 degrees C. It is found that Re can promote the complex stacking fault (CSF) formation, which is similar to the previous results after tensile experiments at room temperature. The micro-mechanism of Re promoting the CSF formation has been investigated by means of advanced probe-corrected scanning transmission electron microscopy and energy dispersive X-ray spectroscopy. The local high concentration of Re is observed at CSF regions after tensile experiments both at room temperature and 750 degrees C. The first principles calculation results further indicate that low concentration of Re increases CSF energy, while high concentration of Re decreases CSF energy, which is consistent with the experimental results. (C) 2020 Elsevier B.V. All rights reserved.