Strength-ductility synergy in two-dimensional gradient nanotwinned metals

XY Ding and ZL Yang and Y Yang, MATERIALS TODAY COMMUNICATIONS, 42, 111456 (2025).

DOI: 10.1016/j.mtcomm.2024.111456

Heterogeneous micro/nanostructure designs demonstrate effective strength-ductility synergy in many metals and alloys. However, coupling multi-type gradient structures in multi-spatial dimensions remains an untried strategy. Here, a dual-gradient nanotwinned (DGNT) structure is proposed and designed, coupling the grain size gradient and the twin thickness gradient in two spatial dimensions (2D). The molecular dynamics (MD) simulation results indicate that the DGNT structure exhibits higher strength and an increased dislocation density compared to that calculated by the rule of mixture (ROM) during tensile deformation. The plastic deformation process of the DGNT structure has a strengthening mechanism dominated by jogged dislocations, as well as a grain coarsening mechanism due to stress-driven grain boundary (GB) migration, whereas single gradient nanotwinned (SGNT) structures do not have both strengthening mechanisms. This work suggests that integrating multi-type gradient structures in multi-spatial dimensions could be a potentially effective strength-ductility synergy strategy.

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