Revealing the Void Formation Mechanism during Superplastic Deformation of a Fine-Grained Ni–Co-Base Superalloy

The mechanism behind void formation during superplasticity remains a subject of uncertainty. This study presented a novel insight into the void formation in a fine-grained Ni–Co-based superalloy during superplasticity. It was observed that the dissolution of γ′-particles resulted in the creation of vacancies due to differences in atomic size between the matrix and the particles. These vacancies acted as inclusions, leading to the formation of micro-voids. Notably, excessive void formation correlated with higher particle dissolution was experimentally observed, highlighting a direct relationship between void formation and particle dissolution.