Nucleation Sites in the Static Recrystallization of a Hot-Deformed Ni-30 Pct Fe Austenite Model Alloy

Abstract

In the present study, the nucleation of static recrystallization (SRX) in austenite after hot deformation is experimentally analyzed using a Ni-30 pct Fe model alloy. In agreement with the predictions by current models, nucleation rate exhibits a strong peak, early during SRX. Whereas such an early peak is explained by current models by the saturation of nucleation sites, this condition is far from reached, even after the peak declines. In addition, triple-junction and grain-boundary sites are shown to make a quantitatively similar contribution to nucleation. However, for a given boundary between deformed grains, nucleation predominantly starts at one of the triple junctions. Triple-junction nucleation initiates by strain-induced boundary migration of the nucleus (bulging) along one of the boundaries at the junction. Annealing twin boundaries contribute negligibly to nucleation through their grain-boundary sites. By contrast, their junctions with the boundaries of the parent grains do play a relevant role. The earlier nucleation at the triple junctions is attributed to the higher dislocation density observed around them, and the energy of the boundary consumed by the bulge. Both the maximum and average number of nuclei formed per boundary between deformed grains increase with increasing boundary length.

Investigation of Recrystallization Kinetics in 1050 Al Alloy by Experimental Evidence and Modeling Approach

“…This can be caused by the presence of an inhomogeneous driving pressure throughout the microstructure. A similar microstructural phenomenon was reported in the literature, as well throughout the course of annealing [58]. With an increase in annealing time, recrystallization tends to progress, and a high number of recrystallized grains are observed in the deformed matrix.…”

Characterisation of Microstructure and Special Grain Boundaries in LPBF AlSi10Mg Alloy Subjected to the KoBo Extrusion Process

“…Recent experimental evidence also points to the significance of strain-induced boundary migration (SIBM) in enhancing the frequency and distribution of CSL boundaries [49][50][51]. While the migration of grain boundaries during primary recrystallisation involves the formation and growth of nuclei with different orientations, SIBM leads to the creation of stress-free regions with the same orientation as the parent grain [52].…”