Correlation between initial microstructure and serration characteristics in GH4169 alloy: Insights from activation energy analysis

This study investigates the relationship between initial microstructure and serrated flow in GH4169 alloy. Fine-grain (FG) and coarse-grain (CG) microstructures were obtained via solution treatments at 960°C and 1050°C, followed by tensile testing at 300–500°C. FG specimens exhibited more pronounced serrations, higher critical strains, and larger stress amplitudes due to enhanced dislocation–solute interactions and the presence of lamellar twins. The activation energy for serration was lower in FG (54.1–59.6 kJ/mol) than in CG (67.8–73.3 kJ/mol), indicating easier serration onset. δ-phase precipitates in FG also influenced deformation behavior. These findings clarify microstructural mechanisms and inform alloy design.