The highly twinned grain boundary network formation during grain boundary engineering

• Coexistent microstructure of recrystallized GBs & trace of disappeared original GBs.
• GB network evolution & grain-cluster growth during GBE.
• Regime of recrystallization during GBE processing.

Grain boundary (GB) engineering was carried out on a Ni-based alloy with pre-precipitated carbides at GBs. Microstructure with coexistence of ∑3n boundaries formed during annealing and traces of disappeared original GBs were observed during GB-engineering. The newly formed ∑3n boundaries are in different positions with that of disappeared original GBs, which indicates the recrystallization front GBs moved into the deformed matrix and swept away original GBs. It is a typical recrystallization process rather than GB decomposition. Strain induced boundary migration initiated the recrystallization. Grain-cluster formed with the continuous occurrence of twinning-events in the wake of the migrating recrystallization front GBs during sweeping away the deformed matrix. Finally large grain-clusters with highly twinned interconnecting ∑3n boundaries were formed.