Formation of nanograins in Ni-Co based superalloys compressed quasistatically at high temperature

In this study, the performance of hot compressive deformation was investigated in two newly developed Ni-Co based superalloys having different stacking fault energy (SFE). It is interesting to discover that nanograins (NGs) can be produced in superalloy deformed at high temperature and relatively low strain rate. With the decrease of SFE and strain rate, the formation of NGs will be promoted obviously, leading to the negative strain rate sensitivity of compressive stress in superalloys. The NGs, generated through the fragmentation of subgrains by microtwins, may become a candidate choice for dynamically strengthening superalloys at high temperature. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.