Modeling the mechanical properties of FCC polycrystalline metals with hierarchical twins

Abstract eng:
Experiments demonstrated that the polycrystalline face-centered cubic (fcc) metals with hierarchical twins performed the higher yield strength with keeping a good elongation. In this work, the extended-dislocation density-based plastic model for constitutive description of nanotwinned fcc metals is applied to simulate the twin spacing and grain size-dependent mechanical properties such as the yield strength and ductility in hierarchically nanotwinned fcc metals. A analytical model on nucleating the deformation twins is also addressed to predict the critical twin spacing in the lowest twin lamellae for generating the subordinate twins. The numerical results show that the global flow stresses are sensitive to the twin spacings in different levels and the grain size. The existence of the hierarchical nanotwins gives rise to the significant enhancement in the strength, and the predicted failure strain decreases with decreasing the twin spacing. The size-dependent critical twin spacing for generating subordinate twins is also studied in details.

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