Abnormal grain growth mechanisms in wrought nickel–based superalloy via semi–in situ EBSD: New perspectives

Abstract

The formation process of abnormally large grains (ALGs) in wrought nickel-based superalloys was firstly captured through semi-in situ EBSD characterization. Under the combined influence of the grain energy field and elevated temperatures, high-GOS (grain orientation spread) values grains restricts the growth directions of adjacent grains with low-GOS values. Relatively clustered low-GOS values grains (0–0.5°) with similar orientations merge through grain boundary migration and grain rotation, forming ALGs. The propagation of twin boundaries facilitates the growth of ALGs. This study proposes a novel mechanism for the formation of ALGs, providing guidance for controlling the occurrence of abnormal grain growth.