Effect of twin nucleation and twin on the recrystallization of a nickel-based superalloy during hot compression

The nucleation mechanism of deformation twin (DT) and annealing twin (AT), and the effect of twins on recrystallization were studied comprehensively for Nickel-based superalloys during dynamic recrystallization (DRX). The aim is to improve the understanding of microstructure evolution during hot deformation. Hot compression tests were carried out at the temperature of 900-1150 degrees C with the strain rate of 0.01-1 s-1 for a Nickel-base superalloy. The results show that the DT and the E3 boundary exist simultaneously in the DRX stage. DTs are nucleated by the rotation of Franck partial dislocations and the decomposition of perfect dislocations. The DTs hinder the movement of dislocations in deformed grains and promote the nucleation of DRX grains. E3 boundaries associated with stacking faults are formed at recrystallized grain boundaries. In the condition of continuous DRX (CDRX), the E3 boundary changes the grain orientation and restrain the CDRX nucleation. While for the discontinuous DRX (DDRX), the E3 boundary provides an additional nucleation site and increase the nucleation rate. In addition, the comprehensive effect of DTs and ATs can promote the DRX nucleation, for which increase at first and then decrease with nucleation mechanical transform from CDRX to DDRX.

Automated summary

This study comprehensively investigated the nucleation mechanism of deformation twin (DT) and annealing twin (AT), and their effects on recrystallization in Nickel-based superalloys during dynamic recrystallization (DRX). The results showed that DTs were nucleated by the rotation and decomposition of dislocations, hindering the movement of dislocations in deformed grains and promoting the nucleation of DRX grains. ATs formed at recrystallized grain boundaries and had different effects on continuous and discontinuous DRX. The comprehensive effect of DTs and ATs promoted DRX nucleation, with varying effects depending on the nucleation mechanism.