Interfacial dislocation networks in nickel-based superalloys: The hidden link between moiré patterns and sample sizes

Nickel-based single crystal superalloys exhibit exceptional yield strength and creep resistance owing to their distinctive two-phase microstructure. This in silico study reported the hidden relationship between the moiré patterns and sample sizes, which govern the formation of interfacial dislocation networks (IDNs). The moiré superlattice arises from lattice misfit, and its compatibility with the γ′ phase size determines the integrity of IDNs, resulting in size-dependent dislocation patterns. Smaller models (size < 25 nm) display discrete dislocation networks due to high residual stress, while larger ones (size > 25 nm) maintain uniformly distributed perfect dislocation networks. These initial IDNs contribute to pseudo-elastic behavior and influence the dislocation activities. Specifically, smaller models experience intensified dislocation pile-up, resulting in higher plastic strength and lower ductility. This study provides insights into γ′ phase size effects on moiré patterns and mechanical behaviour across the elastic to plastic regimes in nickel-aluminium superalloys, offering valuable guidance for their modeling and experimental design.