Tracking meta-dynamic recrystallization in a Ni-based superalloy using timeresolved synchrotron X-ray diffraction

Abstract

The drive towards more sustainable aviation has gained traction as the global aviation industry expands alongside increasing demands to reduce carbon emissions. This drive has pushed research in materials science aimed at developing alloys capable of withstanding high operating temperatures while maintaining metallurgical stability. The nickel-based superalloy Haynes 282 has emerged as a promising material for use in aero-engine applications. Recrystallization plays a critical role in determining the final microstructure and, consequently, the mechanical properties of metallic materials. This project aims to develop computational methods for studying the dynamics of meta-dynamic recrystallization in Haynes 282, to gain a deeper understanding of how the recrystallization process evolves. The superalloy samples were first deformed at elevated temperatures. Right after the deformation stopped, in situ synchrotron X-ray diffraction (XRD) measurements were performed while maintaining the constant deformation temperature. Diffraction patterns were recorded as a function of time. A method was developed to separate the signal into contributions from the deformed and recrystallized grains. This enabled the calculation of the recrystallized fraction, and the tracking of recrystallized grain evolution over time. These analyses were applied to samples deformed at different temperatures. For the sample deformed at 1100 °C, the recrystallized fraction increased rapidly, from an initial average of approximately 5% to 90% within 120 seconds. Higher deformation temperatures resulted in faster recrystallization kinetics and higher final fractions. The progression of new grains and their size distribution was also studied, showing an increase in both the number of grains and their average size over time. The results were compared to previous experimental measurements of Haynes 282, where electron backscatter diffraction was used to quantify the recrystallization and grain growth. The findings of this project align with conclusions previously drawn. The methodology developed in this work demonstrates that time-resolved synchrotron XRD data can be used to effectively study recrystallization, enabling high temporal resolution and potentially greater sensitivity to small grains.