Twin-boundary-spacing-dependent strength in gradient nano-grained copper
Y Tian and FC Ren and F Chen, MATERIALS TODAY COMMUNICATIONS, 33, 104836 (2022).
Twin boundaries acting as efficient barriers for dislocation propagation can significantly improve the strength of conventional polycrystalline materials, which peaks at a critical value. Whether such a critical value also exists in heterostructured materials is poorly understood. In this study, molecular dynamics simulations are performed to reveal the underlying deformation mechanisms of gradient nano-grained materials with different-sized twins. The results indicate that the critical twin boundary spacing where the strength begins to soften decreases and the maximum strength of the material increases with the declining of the gradient. The plastic deformation mech-anism below the critical value is dominated by the nucleation and emission of twinning partial dislocations parallel to the twin boundary at the intersections of twin and grain boundaries. The high-density twin boundary spacing destabilizes the grain boundary architecture, resulting in a decline in strength.
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