On the Coupling between Recrystallization and Precipitation Following Hot Deformation in a γ-γ' Nickel-Based Superalloy

Postdynamic recrystallization and gamma' precipitation during cooling from gamma' supersolvus temperature after hot compression were studied in the AD730 (AD730 is a trademark of Aubert et Duval Company in Paris, France) gamma-gamma' nickel-based superalloy. Emphasis was on not only both phenomena as distinct mechanisms but also on their mutual influence in terms of physical mechanisms. The growth of gamma' precipitates is hastened in the unrecrystallized grains compared to the recrystallized ones. This could possibly be attributed to the higher dislocation content acting as high-diffusivity paths. Postdynamic recrystallization is not prevented by Smith-Zener pinning of the recrystallization front by the gamma' precipitates. Instead, the recrystallization front dissolves gamma' precipitates, which then reprecipitate discontinuously or continuously and coherently with the surrounding gamma matrix in the recrystallized grains.