Recovery facilitated by interphase boundary motion circumvents recrystallization in superalloy single crystals
Hongfei Zhang, Kai Chen, Sicong Lin, Rui Fu, Bozhao Zhang, Jun Ding, Zongqiang Feng, Xiaoxu Huang, E. Ma
Abstract
Dislocation recovery lowering the driving force for recrystallization would be able to suppress the latter in Ni-based superalloy single crystals, but was believed unlikely due to their low stacking-fault energy. Defying this traditional wisdom, here we show that efficient recovery can be realized once the γ′-precipitates start to dissolve. Our microscopy evidence tracking the distribution/configuration of dislocations reveals that the shifting γ/γ′ interphase boundaries release the dislocations trapped there, facilitating their annihilation and rearrangement into low-energy network configurations. Our finding explains the success of a recent recovery protocol that kept superalloys as single crystals after supersolvus homogenization heat treatment.